An incline squat rack is very similar to a regular squat rack. It is an apparatus that holds up two vertical posts that have pegs at varying heights. The pegs are used to hold barbells. The only difference with the incline rack is that the two posts are slightly angled so that they are further away from you at the top.

Angled smith machines are usually 7-12 degrees inclined, which is still very up and down, of course, but having this slight incline of the bar path will allow you to have a more natural squat bar path. Nevertheless, your feet will still need to be a little forward, just not as much as with a straight bar path smith machine.