there is no difference between the business requirement and 
functional requirement..both are the same things.

BRS includes the cusstomers specified high level business
objectives fr which the system to b constructed.it only
represents customer expectations.
where as in functional req the business objectives are
analysed and system level technical specificaations are
derived.it has both functional and non functional features
to b constructed in system.

Requirement(BRS):- 
     BRS- business requirements specification. Business
analyst will interact with the client and will form BRS
document, 
  It contains
   1.scope of the project
   2.business rules
   3.client requirements in depth.

Initially client will give the req's in their own format
then it will be converted in to Standard format( which we
call as Specification) by which s/w people can understand.
In BRS the req's are defined in general format. where as in
SRS ,the req's will be divided in to modules and each module
contains How many interfaces and screens it can have.
SRS:-
 Based on BRS system analyst will form SRS document, 
   it contains
  1. System requirements along with hardware requirements
  2. Functionality to be developed and
  3. what is input
  4. what is output
  5. what is front end
  6. what is back end
  7. what are the technologies
  8. what r processes how they will interact.

based on sRS document design will be generated.


SRS is a Software /System Requirement specification,it is a
MS word doc. which defines the complete business
functionalities of the particular application
SRS designed by System Anallyst