There are tub/shower installations. And there are shower only installations. There are curbless showers. There are roll in showers. There are shower screens, shower doors, and shower curtains. And showers with none of those.

I have no idea what someone thinks they mean by the use of nonsense terms like a stand up shower. You'd have to ask the person using the term.

I think they are referring to the fact it isnt a tub with a shower in it.

Joanna Gaines uses the term "stand-up shower" in one of the early episodes of Fixer Upper. I'm still wondering what she meant.

If a shower is installed over a tub, you can lie down in it, if you feel like it for whatever reason. Being too drunk to stand, for instance. ;)

Stupid term used only on HGTV!