is it magical?
Yes
The longer answer is that the term resin is a pretty broad term. A resin is a type of polymer, meaning it has certain structure and categories. There are naturally occurring types, such as amber and DNA, as well as synthetic, like epoxy resin (the type I think you’re thinking of). I personally have only really used resin for 3D printing from what I remember. The resin for 3D printing is different than the kind typically used for art. You don’t mix it with a hardener. The way 3D printing resin solidifies is through UV light, because the specific resin used for it is photosensitive. So what you do is you design a part digitally, send it to the printer, and the printer will print it by selectively curing the shape that the layer needs based on the design. There’s advantages to this method over the type most people associate with 3D printing (supports aren’t needed, detail is much much much much finer) but also disadvantages (generally more expensive, generally the print space is smaller, meaning you can only print smaller things).
Okay I babbled on too long

But here’s a couple things printed with resin, vs some on a different type of printer for comparison. I’m sure you can see how much finer the detail is.
Resin:
More standard hobbyist printer: