You seem to try to understand these all at once no wonder you get confused ! Start here and try to understand how each flip-flop works before looking at the next (more complex) variant.
All flip-flops have a lot in common and they're less different than you think. The J-K flipflop is more complex because it can be configured to behave like almost any of the other flip-flops.
Indeed if you look at many different sources you will get confused because not everyone names the signals and states in the same way. So PICK ONE and continue from there. When a designer uses a specific flip-flop it is always the datasheet for that particular flip-flip which matters. Only the datasheet describes the behavior, you cannot assume any other description found elsewhere to be correct.
Personally I only look at the truth table for any flip-flop, a proper truth table reveals everything. And here is an example of a proper datasheet for a JK flip-flop you can buy in a chip !
