FF vs. latch
Both flip-flops and latches are digital storage elements.
A latch will follow it's input as long as the latch enable pin is active. When LE goes inactive, the latch retains or "latches" the last state of the input. Flip-flops (aka bi-stable multivibrators) only change state when the input clock changes, there is no "follow" mode.
Miro's right to point out there are different types of flip-flops; RS, JK, D, T, also clocked and non-clocked versions. The type D (or data) flip-flops are the most common and are usually positive-edge triggered, JKs are the most flexible and are usually negative edge triggered (in 74xx or CMOS logic).
The flip-flop is often a more useful building block in digital circuits. If you can find an old copy of the "TTL Cookbook" from Don Lancaster, it has a good section describing the different types and operation of various storage elements.
- CAL