All good, a quick Google image search is enough to understand the difference between the 2 shrug. I've seen how calling products the wrong thing can cause a 10k repair bill when a shower has to be ripped out so you aren't the first and you definitely won't be the last.

I have been in the tile sales business for 20 years, directly with the contractors and commercial dealers and installers...I've been to more TCNA and NTC classes than I care to relive. I know my shit. Not about everything but most definitely about the tile world.

Quarry tile is commercial kitchen tile and comes usually red or gray. It comes 6x6 and larger, is usually half inch thick.

This is unglazed porcelain mosaic used on shower floors. None of this is a generalization...I know tile. The thinset thing is just worded weird... We are saying the same thing there. It's an adhesive that provides a mechanical bond to adhere tile to a substrate. It comes powdered in a bag and is mixed with water to make a spreadable glue...yes applied with a trowel.

How is this a top comment? None of this is true. This is an unglazed porcelain... Close to Quarry but not. Tile is laid WITH thinset not ON it.

Also, it being laid on concrete is perfectly acceptable. I'm not sure what you assumed it should be laid on but even, clean concrete is the best substrate for tile. None of this has anything to do with cleaning grout. Grout is cementious just like concrete so using a cleaning product is mostly useless, especially if it was a lower grade cementious grout. Lifting stains with steam is much more effective. You can also buy an epoxy colorant and tape and paint the joints if it has become discolored. FYI.... ALL cementious grouts will become discolored eventually. You can grind it out and regrout, color it with epoxy colorant, steam it or just sanitize and move on...

I'm actually more worried about the transition between the 2 tiles, how do you not stub your toe on that? Tiles shouldn't be different heights without the use of a transition. EDIT: I guess this is a step down into your shower after looking closer. If you're worried about this being on concrete because it's the shower floor....the waterproofing is under the mud bed which is what is directly under the tile and thinset and looks like concrete.

Is that a wood base... In a shower?

Plus... You get the warranty with all set. This is the route I'd go. You can grind the rest of the glue down or use a primer over the top as well. Not that it's totally necessary but it's an option.