CAT5 and CAT6 are the two most common types of cable networks today.
The main difference between the two categories lies in the technical specifications of the cable: CAT6 provides higher performance level and is preferable in high speed networks. The largest number of windings per unit length and higher quality of shielding allow the CAT6 cable to be more tolerant in places where electrical interference is a problem.
Both cables covering distances up to 100m, although CAT6 can handle longer distances, it is recommended anyway to maintain lengths up to 100m. 1000Mbps speed can be easily obtained with both cables, but because of the frequency is always better to use CAT6 cable, shielded from higher.
In conclusion, if the distances are short and speeds below 100Mbps, in terms of price / performance ratio CAT5 is probably the best solution.