What's the differencr between UV resin used for crafts, the one used in 3d printers, the one used in nails and the one used in our teeth by dentists?

Why do I have to use all possible different protection equipment (gloves, masks, ventilation and glasses) when printing in resin, but then people put uv resin directly in their fingers? And what about the ones that go in people's mouths? It has to be different right?!

Also didn't even asked about kids TOYS, it wouldn't be a thing if UV resin was so dangerous, right? RIGHT?