Why does my song sound different in logic, then in pro tools?

I've been producing, and mixing my track in logic, and then to master it I moved it into pro tools. I work faster in pro tools, but I wanted to try producing and mixing in logic.



I grouped all my similar tracks into one region. (bass, synth, percs, etc. )



I bounced the stems, as individual tracks, and then moved them into pt. When I did, all the volumes sounded off. Some instruments were louder than they should, and some parts quieter than they should. I bounced the song, and played it on my home sparkers, and it sound all off.



Now why is that?



I could go ahead and remix the song in pt, or I can take the time to master it in logic.

Why does my song sound different in logic, then in pro tools?