orgasms

Okay so I've masterbated as in rubbing my clit but why is it that when I get eaten out it's always like I'm on the verge but never jump off the cliff like even when I cum when he eats me out it isn't like when I stimulate my clit that I actually feel like I'm cumming when he eats me out ill cum and he'll tell me but I won't notice when it's happening but I'll still have the after affects like throbbing clit and wanting to pee