Super Mario 64 - Better game feel, better pacing
Ocarina of Time - Better Atmosphere, better ost, better lighting.
Twilight Princess Wii- Better lighting, better atmosphere, motion controls are additive.
Metal Gear Solid - Better ost, better voice acting, better balance/design, better tone, better cinematography.
Starfox 64 - Better voice acting, better ost.
Resident Evil 2 - Survival horror made it way more tense, love the camp/charm, better pacing, better ost, im glad Remake 2 exists tho.
Demons Souls - Better artstyle, better ost, better atmosphere.
Conkers Bad Fur Day - not as censored, better artstyle.
Spyro 2 - Better character designs for the worlds npcs, Hunters VA is worse, they cut "Wyaiyaiyow" chant from iconic monk level.
Mass Effect Originals- Better Lighting, cutting Ass shots, making all classes able to use all weapons, poor level up balancing, cutting back on "Enemies Everywhere", "Go go go" and "I will destroy you".
Halo - Better Atmosphere, better lighting.
Im sure theres more im forgetting too, ill add more if needed. Most remakes lose the soul of the video game which is critical to the artform and therefore damages the understanding of newcomers how good some of these games truly are.