In other words, you are comparing which instrument is harder to play
They both have 12 notes, and how they are played is up to the musician.
They can make it as hard or as easy as they want.
Tell your guitarist and keyboardist to stop arguing and just get on with the jamming/practice/whatever :P
What he said ^
If your bandmates are going to argue over some little crap like that, then tell them to either get out of the band and garage, or shutup and make orgasmic music. NAO.