Ab rhymes with:
bab, babb, cab, colab, crab, crabb, crabbe, dab, drab, fab, flab, gab, glab, grab, grabbe, jab, knab, knabb, krabbe, lab, labbe, mab, macnab, mcnab, mcnabb, nab, nabb, prab, prefab, rab, rabb, sabb, scab, schab, slab, stab, tab, tabb
Ab sounds like:
ababa, abba, abbe, abbey, abbie, abby, abe, abee, abie, abio, abo, abou, above, abu, ahab, ape, apopa, app, appia, aube, ava, ave, avey, avi, avia, aviv, avow, awb, ayoub