SE-1 ,BE-1 , AE-1 are well preplanned before attaching (i.e. Through press release before a long period time).
And EX-1 are added without must planning (i.e.Through decision of high level official's And/Or press release.). But no coach added just before dep. time. on immediate basis.
#This is my observation correct me if i am wrong.
#SE-1 Or EX-1 Both are the same....
more... But I Am just trying to differentiate the little ambiguity between them.