"Left alone" is not an option.
In this case, "remaster" will include making basic changes to stuff like UI and controls to bring the game inline with modern games, and the graphics will be slightly improved by repainting the game models, but new, higher poly models won't be made.
And "remake" is starting from scratch. It can be a faithful remake or it can reimagine large swaths of the game. Graphics and gameplay will be up to current standards.
In this case, "remaster" will include making basic changes to stuff like UI and controls to bring the game inline with modern games, and the graphics will be slightly improved by repainting the game models, but new, higher poly models won't be made.
And "remake" is starting from scratch. It can be a faithful remake or it can reimagine large swaths of the game. Graphics and gameplay will be up to current standards.