Fires of Invention has this line of text:
You can cast spells only during your turn and you can cast no more than two spells each turn.
Golos, Tireless Pilgrim has this line of text:
2WUBRG: Exile the top three cards of your library. You may play them this turn without paying their mana costs.
If I activate Golos's ability with Fires of Invention on the battlefield, do the non-land cards that I play count as spells for Fires of Invention?
My intuition says "yes", making these two cards a nonbo. However, Magic's wording is very strict, e.g. "put [card] into your hand" is different from "draw", so I'd like to make sure that "play" and "cast" are indeed the same thing, with the only difference being that I can "play" a land, but cannot "cast" it.