Questions about Resin AM parts

What are resin parts exactly?

I'm currently in the boatbuilding industry after spending 15 years in Engineering...to me "resin" could mean a number of things.  For instance conifers have resin; epoxy is called resin; polyester or vinylester are resins used in fiberglass; polymers are resins...get what I'm saying

I know I'm allergic to polyester/vinylester resins used in fiberglass work (and I'm not sure if it's truly the resin or the hardener...but it makes me sick as a dog ).

So what are "resin" parts made from and what precautions do most of you take when working with them?

Thanks for the information!