FPS difference is neglible, but does exist. As for quality, most reviews seem to agree that both have their turns to shine over the other and are more or less on same level.Inferior = Slower and worse quality.
Also FSR is clearly superior in the fact it doesn't require specialized hardware, which based on performance has little to no benefits in this case, to run.
It's quite often one company does something and other(s) follow(s) later, temporal scalers aren't the first and won't be the last where this happens for GPUs. Sometimes it's AMD first, sometimes Intel, sometimes NVIDIA.And it took nVidia so long because they have done the whole work alone and from the start. Where was AMD 2 1/2 years ago?