Hi:

There is no real difference between the three.   An integrated set of data flow diagrams, entity relationship diagrams, and logical data dictionary, for example, can be call a SRS, BRD, or FRS.   The reason three terms exist for the same thing is largely politics, not logic.

Tony

ViK:

I have been studying the BRD templates and SRS.  To me it appeared that early parts of SRS emerged as BRD.  On closer examination I found that BRD has Business / User Focus where as SRS has System or Solution focus.  SRS describes WHAT the System should be CAPABLE of doing to meet the business needs. 

A business Analyst who has good analysis skills should be able to generate BRD (including the Use Case Descriptions) and need not worry about Sequence Diagrams and Design Class Diagrams which belong to SRS.

This distinction is useful to define the responsibilities and skills of BAs and Developers.  I have a set of FIVE expandable & collapsible templates for BRD which can be created and refined iteratively.  I use them for my professional work and teaching / consulting.  They speed up BA & RE activities while providing comprehensive and high-precision specifications.

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