Norcal is slightly faster. (27/45 compared to tenny's 25/42 speed caps)
BB3 mid range compared to mid BB2 Range
Spread on both is crap. Probably worse on the Norcal.
16" Mark 6Ls Hits like a bus. 14" Mark 7 Ls hits like a bike. You have to land the salvo first.
Stronger Ship structure, it can take more hits.
First Usable AA battery for the Line you've chosen. 10 t slots in 5 per side 3 upper 2 lower between the 3 upper. With 70 space, allowing guns like the 3" 70s, 5" 38 Cal Mark 38s and the 5" 54 Cal Mark 16s, of course HH fit well too :P
NorCal has a slight Alaska like Glass-Jaw, its hitbox is hugh for the tier. Not Hood hugh, but hugh. It also doesn't turn as fast making it hard to dodge salvos. It really relies on its speed and AA for making strong pushes.
Decent Overheat time compared to the Tennessee.