Р-58

БОЛЬШАЯ РАЗНИЦА NP sing only subj-compl with бытье ( subj: это, infin, or subord clause or clauses) fixed WO

some circumstance (action etc) is entirely different from another previously mentioned circumstance (action etc): это большая разница - there's (it makes) a big difference.

Ты согласился перейти в другой отдел сам, а меня заставили. Это большая разница. You agreed to transfer to another department, but I was forced to transfer-there's a big difference.