seems I heard that comb filtering was used to create chorus effect, or was it flanging
Both of these are delay related; the difference is in the amount.
The closer in time the two signals are, the higher the frequency(s) of destructive interaction. A flange effect is definitely comb-filtering. A delay of a couple milliseconds is used - often a variable delay - and the resulting sound is the changing nature of the comb-filtering interaction.
Chorus effects can be more complicated, using combinations of delay (usually longer than flange delay), detuning, and other tricks.