Hi!
The Fire HD 10 (5th gen) is not the same as the Fire (5th gen), the main difference being the screen size. The Fire HD 10 has, as the name suggests, a 10 inch screen, while the Fire only has a 7" screen. The best way to tell them apart if you're unsure is to measure the screen size diagonally.
Also, as far as I know you can't replace just the glass because it's glued to the screen and because it's very hard to separate them (without breaking the screen) without professional tools.