Corset + Tudor|Elizabethan
^Stays. Not a corset, Stays. Corsets were invented later.
The difference is how they are made, right?
Yep, and the kind of shape they create. Stays create a very cone shaped figure, while corsets create a more hourglass shape. Also stays are usually either one piece laced in the back, or laced in the back and front. And corsets rely on the two piece busk at the front and lacing in the back.
I think stays tend to end at the waist with the point extending beyond, while corsets typically go from the bust to just over the hips. (Depending on what era of corset. The late 1800s corsets went well past the hips.)
And this fantastic image I found has all the different kinds of shapewear side by side so you can see the differences. The one of the left is a “pair of bodies” or stays, and the middle and right are corsets:
I’m going to stop here before I end up writing a novel.