Have a look at the RN website. 22s and 23s are ASW units. 42s are old air defence destroyers. 45s are new destroyers. To go into the major differences (propulsion, weapons, aircraft etc) would:
a. Take ME too long.
b. Mean YOU get no benefit from doing the research yourself.
c. Take me away from thinking up another thread title that's as pointless as this one.
d. I can't think of a "d".