Ah, not retinol, retin A.
None of the retinol compounds will be as effective as the Retin A, because the chemical is somewhat different.
Like for like it is the active ingredient that matters, the rest is just packaging. The higher the concentration of the retinol the more effect I'd expect it to have.....but bear in mind that you might end u with sore skin if you use too much.
Buy one you like the smell of/feel of, with the highest concentration that your skin can tolerate. If there are two that meets your needs, get the cheaper one!
Only the active ingredient really matters, the rest is just marketing bollocks.
BUT STAY OUT OF THE SUN