In lang=en terms the difference between flap and beat
is that
flap is the female genitals while
beat is boring.
In transitive terms the difference between flap and beat
is that
flap is to move (something broad and loose) back and forth while
beat is to indicate by beating or drumming.
In intransitive terms the difference between flap and beat
is that
flap is to move loosely back and forth while
beat is to move with pulsation or throbbing.
As an adjective beat is
exhausted.