The term "game loop" usually refers to the programming pattern that is the core of most game engines, while the term "gameplay loop" is a game design concept about how game and player interact. However, in a pure game design context, you sometimes have people say "game loop" when they actually mean "gameplay loop". So when you are talking specifically about game design and not about the implementation, the two terms are synonymous.
If you want to differentiate between gameplay loops at different scales of the design, then it is common to refer to them as "inner gameplay loops" and "outer gameplay loops". For example, when you design a 4X game like civilization, then you might describe an inner gameplay loop of picking units and moving units, while having an outer gameplay loop describing the turn progression (move units -> manage cities -> click next turn -> watch opponent actions -> read event messages). Or in an MMORPG you might have an inner gameplay loop of "pick enemy -> kill enemy -> collect loot" while you have an outer gameplay loop of "talk to questgiver -> go to quest location -> kill enemies -> return to questgiver".