Both old and new standards cover essentially the same topics.
However, there are some important differences. Some of these
are discussed below.

Structure of standard

Perhaps the biggest difference between the old and the new standard
is the structure. This is because the new edition uses the new Annex SL
template. According to ISO, all future management system standards
(MSSs) will use this new layout and share the same basic requirements.
As a result, all new MSSs will have the same look and feel.

A common structure is possible because basic concepts such as
management, requirements, policy, planning, performance, objective,
process, control, monitoring, measurement, auditing, decision making,
corrective action, and nonconformity are common to all management
system standards. A common structure should make it easier for
organizations to implement multiple standards because they will all
share the same basic language and the same basic requirements.

Context of the organization

Unlike the old standard, the new one expects you to understand
your organization's external context and its internal context before
you establish its environmental management system (EMS). This
means that you need to identify and understand the external issues
and the external environmental conditions that could influence your
organization's EMS and the results that it intends to achieve. It also
means that you need to identify and understand the internal issues
and internal environmental conditions that could influence your
EMS and the results in intends to achieve.

The new ISO 14001 2015 standard also expects you to identify the
interested parties that are relevant to your EMS and to identify their
needs and expectations. Once you've done this, it expects you to
study these needs and expectations and to figure out which ones
have become compliance obligations.

But why is all this necessary? It's necessary because your EMS
will need to be able to manage all of these influences. Once you
understand your context, you're expected to use this knowledge
to help you define your EMS and the challenges it must deal with.

Risk planning

Unlike the old standard, the new ISO 14001 standard expects
you to determine “risks and opportunities”. So what does this
mean and what does the new standard expect you to do?

It expects you to start by establishing a risk planning process. It then
expects you to use this process to identify risks and opportunities
related to your organization’s unique context, its interested parties, its
compliance obligations, and its environmental aspects. It then expects
you to define actions to address all of these risks and opportunities.

And to make sure that these actions will actually be carried out, it asks
you to make these actions an integral part of your EMS processes, and
then to implement, control, evaluate, and review the effectiveness of
these actions and these processes.

While risk planning is now an integral part of the new ISO 14001
standard, it does not actually expect you to implement a formal
risk management process.

Preventive action

The new ISO 14001 standard no longer uses the term preventive action.
We’re now expected to use risk planning concepts and to think of the
entire EMS as a system of preventive action. ISO 14001 2015 section
A.10.1 says there is no longer a single clause on preventive action
because “One of the key purposes of an environmental management
system is to act as a preventive tool. This concept of preventive action
is now captured in 4.1 (i.e., understanding the organization and its
context) and 6.1 (i.e., actions to address risks and opportunities).”

So, according to the new standard, these two sets of requirements
cover the old concept of preventive action. Evidently, once we realize
that the entire EMS can be used to manage risks and opportunities, we
no longer need a separate clause on preventive action. It's redundant.

Documented information

The new ISO 14001 2015 standard has also eliminated the long
standing distinction between documents and records. Now they're
both referred to as “documented information”. Why ISO chose to
abandon two common sense concepts and replace them with one
that is needlessly awkward and esoteric is not entirely clear.

According to ISO's definition, the term documented information
refers to information that must be controlled and maintained. So,
whenever ISO 14001 2015 uses the term documented information it
implicitly expects you to control and maintain that information and
its supporting medium. However, this isn't the whole story.

An annex to the new ISO 14001 2015 standard (A.3) further says that
“this international standard now uses the phrase 'retain documented
information as evidence of' to mean records, and 'maintain documented
information' to mean documentation other than records.”

So, whenever the new ISO 14001 standard refers to documented
information and it asks you to maintain this information, it is talking
about what used to be referred to as documents, and whenever it asks
you to retain this information, it is talking about what used to be called
records. So sometimes documented information must be maintained
and sometimes it must be retained (contrary to what ISO's official
definition says).

So, while the official definition of the term documented information
abandons the distinction between documents and records, through
the use of the words "maintain" and "retain" and because of what this
means (according to Annex A), the main body of the standard actually
restores this distinction. In other words, while documents and records
were officially kicked out the front door, they were actually allowed
back in through the back door.

Procedures

The old ISO 14001 standard asked organizations to establish
a wide range of procedures. These included an environmental
aspects procedure, a legal requirements management procedure,
an awareness procedure, a communications procedure, a documents
procedure, an operational procedure, an emergency preparedness
and response procedure, a monitoring and measurement procedure,
a compliance evaluation procedure, a nonconformity management
procedure, a record keeping procedure, and an audit procedure.

Now, only one procedure is left. The new ISO 14001 2015 standard
asks you to establish an emergency preparedness and response
procedure in section 8.2, and that's the only one.

Instead of asking you to write procedures, the new standard
expects you to maintain and control a wide range of documents
(i.e., documented information). Since the new standard doesn't tell
you what to call these documents, you can call them procedures
if you like. And, of course, you still need to have documents except
that now they're called “documented information”. So, while on
the surface this looks like a radical change, it probably isn't.

Other clarifications and modifications

The old ISO 14001 standard asked you to "define and document the
scope of  its environmental management system" (4.1), but it didn't
say anything about how this should be done. The new ISO standard
clarifies how this ought to be done (4.3). It now asks you to consider
your compliance obligations, your corporate context, your physical
boundaries, your products and services, your activities and functions,
and your authorities and abilities when you define the scope of your
EMS. And it asks you to include all products, services, and activities
that have significant environmental aspects.

The new term "compliance obligation" has replaced the rather
cumbersome phrase: “legal requirements and other requirements
to which the organization subscribes”. However, the meaning is the
same. There are two kinds of compliance obligations: mandatory
compliance obligations and voluntary compliance obligations.
Mandatory compliance obligations include laws and regulations while
voluntary compliance obligations include contractual commitments,
community and industry standards, ethical codes of conduct, and
good governance guidelines. A voluntary obligation becomes
mandatory once you decide to comply with it.

The new standard no longer refers to environmental targets.
According to section A.6.2, "The concept of “target” used in prior
editions of this International Standard is captured within the definition
of “environmental objective”. You can, of course, still set targets and
call them targets if you wish. The only real difference is that the new
ISO 14001 standard thinks of a target as a type of objective.

Life cycle considerations were largely ignored by the old standard.
Now they're central. ISO 14001 now expects you to use a life cycle
perspective to “identify the environmental aspects and associated
environmental impacts of its activities, products and services that
it can control and those that it can influence” (section 6.1.2).

The term “management representative” has been officially dropped.
The management duties and responsibilities that were previously
assigned to someone called a “management representative” may
now be assigned either to one person or to many. Of course, you
may continue to use this job title if you wish.