Well, these are the differences between the two cables...
Category 5 cable can be successfully run for a distance up to 328 feet whereas CAT5e Cable can be run for a distance of 550 feet. CAT5 supports speeds upto 100mbps whereas CAT5e supports speeds upto 1000mbps(1GBps)
CAT5e has all the characteristics of CAT5 cabling, but has been developed to minimize interference and other cabling related problems by wrapping it in STP and S-UTP.
There maybe more differences, but I am not aware of them.