If your 91 then you get to saunter out of class when its over while the rest of us 135 knuckle draggers get to a checkride. At a 121 carrier they take what they want you to know out of the AFM and make a handy dandy POM and study guide for you to learn. They dont want you to know too much, just enough to get from a to b as safely as possible. At a 91/135 operator they give you the AFM and PTM to learn, which is a lot more daunting. What I miss most about flying at the airlines is good old standardization, everyone does the same thing. The checklists are spelled out, duties are defined, it makes everything operate like a well oiled machine. Everything is scripted. When I first made the switch it was tough because some folks were doing things willy nilly which drove me nuts. This is not the General Lee, not sliding across the hood speeding off to the boars nest to hang out with uncle jesse. They probably think i am a checklist Nazi. You have to fly with the same folks over and over and over. The great thing about 121 is you are almost always with someone different ( thank you- no fly list). With 121 flying you fly so much you get into a rhythm which is nice because you get comfortable in the plane, you know it from the rooter to the tooter. Not so much the other way. I think planning is a lot more involved as the others have said above. You fly to so many different places, have to be careful. No dispatcher to back you up. No braking action reports on a snowy day in cornville, no raim in BFE on a ifr day, everybody is going to rifle because the wx sux in ase, be ready for a long line, " well that shore is a fancee lav you got der sir...cant service it..sorry". I dont miss being number 27 in line launching off of 8R, waiting for 3 hours for a slot to fly 130 nm and the whole olympic sport of commuting. But, the planes are nice and the performance will blow the doors off of any airliner out there. Money is good and we are treated well. Im getting used to it. As always results may vary, good luck.