[Tytus Gerrish]

Originally Posted by Lil' Lavery

As Madison said, Holonomic and Mecanum drives can actually be quite different. For instance, the rollers don't even have to be at 45º (different angles will alter the amount of energy that is used when going different directions. A 45º angle results in the movement in both the X and Y axis being equal, but any other angle they would not be).
Basically, a mecanum drive's angled rollers directs some of the energy of motion sideways, and depending on the direction and speed (the vector) of each wheel, you can move your robot in any direction.

45º is simply a rule of thumb you can do it at whatever angle you would like you could even actuate the angle to get some diffrent properties out of the preformance.