They are both retinoids and achieve the same effect. My derm has told me that differin tends to be less irritating but also weaker compared to retin a so start with differin.Do not apply it straight after dermarolling. I would wait at least 72 hours if not a whole week until after most of the swelling subsides.
I have been getting RF microneedling by a professional...I had been doing home derma-stamping/microneedling prior to that. I use the OTC Differin .1%. You only need a prescription for the .3% strength. Myself, for both home treatments and the professional RF, I don't use anything that night. Depending on how I feel the next night, I may resume or wait another night. Either way, it's not like my face is going to fall off. If I were using the stronger .3% (prescription strength) I would be inclined to wait another night to resume. I have been using the .1% for over 2 years now though, so my face is well acclimated to it.