Remasters update a game's visuals and performance with relatively modest investment, while remakes rebuild a game from the ground up with modern technology. Both exploit nostalgia and existing brand recognition, which dramatically reduces marketing and design risk. A remaster might cost a few million dollars and sell on name recognition alone. A remake costs much more but can reach both nostalgic fans and entirely new audiences. The economics are favorable because the game design is already proven, you are essentially de-risking the most expensive part of development.