I've also heard them called gas-start/wood burning.... when it's merely a gas-start fireplace.
I would presume that when they call it gas fireplace... it's strictly gas. Now the question would be is it a ventless-gas fireplace, or is there a true flu??
Ventless-gas puts 100% of it's heat into the room, and a gas-fireplace with a flu sends some percentage of its heat up the chimney. Ventless gas, even those that are a small flame, and mostly decorative, can put a lot of heat into the room, and a smaller room can become oppresively hot rather quickly.