Buying high quality Sherwin Williams paint as a contractor, I've never even heard those names. We use their best interior paint, which is Emerald. I'm extremely impressed and as long as you prime new texture and bad black marks under a white color, it even covers in one coat. Only paint I've found where flat is scrubbable too, even though we usually use one step up in gloss from flat unless the drywall texture is done very poorly.

If you are going to a Sherwin Williams store, I would get their advice as I've always been impressed with them.

You aren't talking about some of their cheap lines like the "special" stuff they sell through Lowes, are you?

Neither of those.

And counterintuitively the Promar 200 is "better" than the 400.

They are both builder grade and you won't be happy with them.

forget the promar crap and go with Cashmere, cheaper than Emerald but very nice paint

It depends on what you want from your paint. For some applications, Pro Mar 200 is fine. Pro Mar 400 is cheaper, but may be fine if you just want to use some cheap paint to put in a room that nobody ever uses or something. If you want, you can even get some Pro Mar 700 which is even cheaper. Sherwin Williams even sells some real crap called Property Solutions which they keep in the back room for contractors that really don't want to spend money and hey that's not even that bad. I had a contractor ask me to paint the basement walls in a rental property he has, and that product was perfect for that. I have used Emerald too. It needed 3 coats over a tinted primer to cover, so it's no Aura!