those two are kind of like cousins - retinol is a type of retinoid. of course it may differ for everyone, but my doctor has given me prescription retinoid which is much more concentrated. honestly I started using it once a week, and then twice a week, and I have no more irritation (make sure to moisturize a lot) with just a pea size amount of the cream.
I don’t think it would be a bad idea to do a retinol serum first, but it is less concentrated so personally I think getting a prescription for retinoid cream would benefit you if your skin needs it. sorry if that doesn’t answer your question lol