You're using graphics solely as a qualifier of remastering vs remaking.
For me, remaking entails some discernable gameplay deviations as a major defining factor, not just aesthetics/graphics.
Final Fantasy 7 Remake and Resident Evil 4 are both Remakes because their gameplay has been completely overhauled. In the latter's case, it still borrows heavily from it's original incarnation, but has changed how certain systems work (like the thing with the collectibles) and even how levels/events play out, and in FFVII's case, it switched from being a turned-based RPG to being an action RPG, which is a huge change gameplaywise.
Reimaginings are part of Remakes, because the game itself is remade but not built quite the same way. Again, Resident Evil for GameCube versus Saturn is a good example: The GameCube Remake added gameplay elements such as Crimson Head zombies, completely changed the layout of the mansion, Lisa Trevor subplot and character/boss battle, and changed puzzles completely.
A Remaster can have a complete engine change and other technical overhauls, but if it decides to follow its original source material faithfully in a mostly 1:1 fashio, perhaps with deviations here and there, then it can qualify as something more along the lines of a Remaster. Xenoblade Chronicles Definitive Edition would fall under this, for instance.
Now something like Another Code Recollection, on the other hand, would truely be teetering the line between a Remaster and a Remake, as it does require overhauling some significant gameplay elements to suit the Switch's format vs. the Nintendo DS, and some pacing changes/gameplay scenarios were rearranged for this purpose.