they differ when it comes to binary digits..its really hard to explain but they doesn't seem to differ much in memory allocation..or is it just my IDE..anyways a 32bit can represent numbers to 4,294,967,296 bytes.. while a 64bit can represent number to 18,446,744,073,709,551,616. but in order to use this power you must have at least 4g of ram...they also differ in CHAR_BIT