Simple computer logic
32- bits max integer values are 4,294,967,295 (4gbs)
while 64-bit max is 18,446,744,073,709,551,615 (65 petabytes)
With a 64-bit Process your CPU has more things to access hence making it run smooth
while 32-bit has less witch is why you max it out
your comp spec are still the same just have more room to do it
Analogy
Say you have a 10000 square feet factory - this is your 64-Bit processor
now you can only use 2000 square feet of it to do work - this is the 32-Bit Program running on your 64-bit processor
now say you rent out the last 8000 square feet of the factory now you have more room to do stuff but doesn't mean its better - upgrading 32-bit to 64-bit.
^see simple^
Even BI knows