It's easy to tell between Ramake and Remaster when thinking of movies.
they're either completely Remade or Improved on new technology.
Remake: Female Ghostbusters
Remaster: Ghostbusters 1984 Blu-ray
If DVD/Blu-ray players had become available/affordable back when they were only releasing movies on VHS, they'd have Remastered the best for DVD/Blu-ray release, not Remade them again with the same actors.
With video games, Remasters would typically mean the same engine/glitches with improved graphics/audio.
Assassins Creed The Ezio Collection (II / Brotherhood / Revelations)
Burnout Paradise Remastered
Sonic Adventure DX: Director's Cut / Sonic Adventure 2 Battle
The Legend of Zelda: Ocarina of Time 3D / Majora's Mask 3D
The Legend of Zelda: Twilight Princess HD / The Wind Waker HD
Sometimes Remasters are so improved that they feel like Remakes:
Halo: Combat Evolved Anniversary
Halo 2 Remastered
Call of Duty: Modern Warfare Remastered
This is just because today the standards are so improved.
They've Remade all the graphics, but not Remade the core engine. It has to be from scratch to be a Remake.
If they ever Remake WaW though, they're definitely gonna need to Remake it. (that old engine sucks)
GTA V and BO3 are also Remasters in comparison to their old gen releases. Same game, enhanced output.
(But of course that isn't the typical example of Remasters, since there's no time frame between their releases)
Crash Bandicoot N. Sane Trilogy
Spyro Reignited Trilogy
Pokémon Omega Ruby and Alpha Sapphire
Resident Evil 1 and 2
Also Majora's Mask 3D has added features, like the Fishing Hole's. but it's still a Remaster if it has the same engine. Updates are just as much apart of the ~improvement. Otherwise Remakes would be easy.
Call of Duty also recreates multiplayer/zombie maps. Those maps themselves are Remakes.
They wouldn't be able to use old low poly/resolution data for today's standard.