In short -
Reds are a smooth, quiet, fast push.
Blacks are reds with more resistance
Blues are a clicky, tactile feel. Slower push, with a fealable bump partway through a push, and a distinctive click.
Greens are blues with more resistance.
Brown - Quiet, tactile switch. Similar ot blues, minus the click
Clear - Browns with more resistance.
I recommend browns for quiet typing and gaming, reds for pure gaming, and blues if you like the clicking noise.