The angle of the seat tube might be significantly different placing the bb and saddle in a different relationship to each other from the other bike.
You mentioned you are trying to get pressure off your hands for numbness. That's not just balance doing that to you. Reach and bar height play a part too. I just recently changed to narrower bars than what conventional wisdom would say are appropriate to me and eliminated some wrist numbness I was having on long rides.
Might help others help you with your numb hands if you describe that actual issue that has you chasing just one possible solution that might be better addressed with another solution.