the comfort seats incorporate every adjustment the sport seats has and then some. the sport seats are firmer and have larger side bolsters

having both (2001 X Sport w/sport seats & 2006 X5 Sport w/comfort seats) I find both to be comfortable (even on long trips, 2000+miles) - I selected the comfort seats in my 2006 because I thought they would be better sitting in east coast traffic (they are) - but the sport seats are great if you like taking turns hard and give you a better bucket seat feel - It all depends on how you like to drive

Just received my X5...the Comfort seats are awesome. Actually I have the active ventelated seats and these things are simply amazing. If you only get one option, this is the one to get. They even have a massage action built in.

i'm guessing the passenger doesn't get the massage...

does the passenger seat have memory?

the massage action is the active seat option

Yes, passenger has exact same functions, including memory (except massage).