I always thought of them as:
classic Egyptian pyramid, 4 smooth sides, rising to a point at the top.
ziggurat as a stack of boxes, each one smaller than the one below it. Like a pyramid built out of legos.
A step pyramid as being sort of in between.
So what are Mayan temples, like those in Chichen Itza?
I always see them called pyramids, but they don’t have smooth sides, and they don’t come to a point at the top. Instead they have a platform on top, with a temple/structure occupying it.
In addition, most of the definitions i find online for ziggurat (type that enough times and that word begins to look really really weird) specifically call it a Mesopotamian structure.
Are there hard lines separating and defining the 3 structures?