difference between requirement and constraint
1 Answer. I am not a business analyst (I'm a software developer) but wil hazard a semi-educated guess: A requirement is something that is desired and fills a business need while a constraint limits choices to fit within an existing space. For example, a requirement might be something like: As a user, I must be able to enter the lengths of two adjacent sides of a rectangle and then click a single button to obtain the perimeter of that rectangle..