Dear Rohan,
The definition of Aspect as per ISO 14001 is "organizations activities, products and services that can interact with the environment and those which have the potential to interact with the environment."
The Impact is the effect of the aspects. As per ISO 14001, one has to identify aspects of all activities and evaluate their impacts. This has to be done considering applicable legal requirements.
Many companies follow SSPD analysis and give ratings on some scale, say 1 to 5:
S - Scale of the problem
S - Severity of the problem
P - Probability of the problem
D - Duration of the problem
Organizations set some cutoff points beyond which the impact of a particular aspect is considered significant. All adverse as well as beneficial significant impacts are listed, and those activities in the adverse impact category are taken for improvement, which is popularly known as an Environmental Management Program (EMP).
The aspects governed by any legal requirements are essentially significant. For those significant impacts generated from those aspects that are either controlled by EMP or, if there is no scope for any EMP, they have a Standard Operating Procedure (SOP).
If you need any more information, you may email me at asudhir17@rediffmail.com. However, please provide some inputs like the products you manufacture, location, processes, and environmental issues in your plant.
Best of luck.
Thanks and Regards,
Sudhir