Not a dumb question. Just ask if you don't know. A lot of times people will just call it a flywheel, even if it's an automatic. So it's good to ask.
the visual difference(just for reference) the flex plate is fairly thin except for the starter ring gear. a fly wheel is really thick, due to the surface for the clutch..
Flywheel is usually either cast or billet, noticeably thicker and heavier, and will have a large smooth surface for the friction disc of the clutch to make contact with. A flexplate is usually just stamped steel with the starter gear welded to it, as was said, the flexplate is used in automatic cars and is basically just a way to connect the torque converter to the crankshaft.