I think Team A would net somewhere in the low 50s win-wise in the NBA. Say 50-53 wins.
I'd put Team B in the high 40s. Say around 47-49 wins. I'd also note that JaVale McGee -- with some solid improvement -- is capable of closing that gap by next season single handedly.
I'd take Team A over Team B but I don't think there is a huge amount between the two teams.