Brian is right and pdedes has the inside track. Rest is marketing.
If BB30...best question or debate is discussing installation method pro and con.

Also...question regarding grease. Same thing. I use Mobil 1 synthetic grease but any basic automotive grease will do.
Many BB's use sealed bearings but never a bad idea to pull crank off the bike once in a while, clean, inspect and regrease...what most cyclists don't do...no PM...they replace upon failure instead.