System requirement specification (SRS):

It is a documented collection of information regarding the flow of working along different modules as well as the overall working of the product with various user cases to better explain the interaction of the prospective user with the IT product.

Functional Requirement Specification (FRS):

This document mentions how a system requirement when transformed into a functionality will become a part of the system.

Business requirement Specification (BRS):

A prospective client has a number of needs from a product pertaining to his organisation's aspirations and planning. These needs maybe existential in nature or may form part of future planning.

Differences between SRS, FRS & BRS

1. As part of development work involved in creating the product, it relates to resources given by the parent company. It consists of requirements asked of the product company from the client side. It consists of demands belonging to the business requirements.
2. The document is prepared by a team of system analysts. The document is a result of close coordination between the development and testing teams. It is created by a team of business analysts.
3. Use cases which define user interaction with the software, form part of this document. Use cases are not part of this document. Use cases are not part of this document.
4. The document explains the stepwise sequence of all the operations inherent in all the modules and sub-modules forming part of the IT product. The document explains all the functionalities for which the application is developed. All the requirements requested by the client complete in all the details are lucidly collected and presented in this document.
5. Always contains references to diagrams and tables. May contain labels and references for diagrams and tables. Not necessary to include references for diagrams and tables.
6. Does not include scope of the product. Does not include scope of the product. Contains future scope of the product keeping in mind the plans for expansion plans of the organisation.
7. Doesn't list anyone from the client or user base. Doesn’t list anyone from the customer side. Lists the user base as well as similar stakeholders from the customer side.
8. This document is derived from BRS. Generally this document is derived from BRS. This document is derived from interacting with customers and taking feedback from them for requirements.