Clear is to Green as Brown is to Blue. The main differences between clear and brown are:
Clear has a larger 'bump'. This means that there's a larger amount of tactile feedback.
Clear has a stronger spring. It provides a springy feel near the bottom of the keystroke which some people find useful when trying not to bottom out.
Both are inherently quiet switches, however Clear is probably quieter as the increased resistance results in a less forceful 'bottom out' sound when the keycap hits the switch housing.
Many people like the clear, some people for its weight and cushiony feel, but most often for the large tactile bump that many prefer to the minimally tactile brown switch. Those that appreciate the bump but not the weight have created the popular Ergo Clear mod where a lighter spring, usually between the Brown and the Clear in weight, is substituted for the Clear's stock spring.
Because you are presumably going to be buying a keyboard stock and not modding switches - this is how you should make your decision:
Would I prefer the lighter Brown (lighter then your average rubber dome - same weight as MX Blues) or would I prefer the heavier Clear (Heavier than most rubberdomes, comparable to MX Green)?
Do I want the extra tactility of the Clear or would I be fine with the smaller tactile bump of the Brown switch?
Buying a couple of the switches from a site such as TheKeyboardCo may help you make this decision, however single switches are not representative of the feel of a whole keyboard.
