What is the difference between clock and pulse?
1.) Generally, when referring to a "clock", the signal in question is a never-ending pulse train with known frequency, amplitude, and edge rates. 

However, a single pulse used, for instance, to initiate the propagation of a data signal through a "D" type flip-flop is often referred to as a "clock pulse" and, in fact, many logic chip diagrams label the clock input "CP".

2.) The term isn't "frequence", it's "frequency", and it was invented in order to indicate the number of generally regular occurrences of an event in a particular unit of time. In the scientific community, the frequency of an occurrence is measured in hertz, with one hertz being equal to one cycle per second.