The two terms of the title are often used somewhat interchangeably (and I’ve been guilty of that myself in the past) but in fact they have rather different meanings, despite their close relationship. Here is a series of fossilised crocodile osteoderms that I picked up a few years back. The term osteoderm literally means bones in the skin and that’s exactly what these are, piece of bony armour that sit in the skin.
Scutes on the other hand are the keratinous sheathes that cover the osteoderms. You can see some of these here in this croc with those bigger chunky scale-like pieces running along the back. That of course means all those fossil ‘scutes’ from things like crocs and ankylosaurs and titanosaurs should really be called osteoderms. In fact while of course claws and similar things do preserve from time to time, and there are bits of horn sheathes etc. out there, I’m not aware of any scutes being known from the Mesozoic (though not working on any of the more obvious groups, I could easily have missed them).