[petrotsky]

fewer, less than <= its all the same

[calenel]

Fewer is for discrete units, such as hours or dollars. Less is for non discrete units such as time or money. Examples:

Fewer hours is less time.
Fewer dollars is less money.

The same rules apply for much and many. You would not say I have too much children which causes me to have fewer money unless you were the product of one of the worst of public schools (not for the children, but for the grammar).