Not at all stupid. It would be easier at a club flying site, where someone could point at the different variations.

Those would include the traditional small "glow" engines, which use alcohol for fuel (mixed with lubricants and other things like "nitro") and come in sizes suitable for training planes, larger planes, and smaller nimble planes. They're labeled "glow" because ignition is catalytic, initiated by the glowing warm element of a glow plug in the combustion chamber.

Also included would be the lightweight gasoline engines, with spark ignition. These mainly come in sizes to power the larger planes.

Electrics are, well.... electric. These motor/battery combinations are available in power ranges from the small to the ridiculously large.

For more particulars, you should see the folks at your friendly local flying field.
Best wishes,
Dave Olson