Tank Car differences

[8D]I have a lot of tank cars on my layout. I’m mostly interested in the “chemical” tank cars. [?]Besides chemical cars having a platform on top, what other differences are there?
Do petroleum cars ever have platforms too? [;)] I realize that the petroleum cars can have one or three domes.
My main interest is in the 40’ cars.[:D]

Don’t forget some tank cars carry corn syrup or vegetable oils. They look like any other tank car, except for the labeling, on the outside but they are glass lined on the inside.

See Tank Car

gsetter - Thanks for the info. I did know about the vegetable oil, since I have one that I usually leave on a siding next to my bakery. But I didn’t know about the “tank car” ref".