kitchen backsplash tile grout or caulking
You might push soap or grime into the gap at the bottom of the cabinets when cleaning the tiles, so it's probably a good idea to seal the gap. I didn't do this in my kitchen and I think intelligent life is evolving in there. 

I'd use silicone caulking instead of grout at the these locations, because it's more flexible, and I'm convinced that there is always some tiny flexing or movement between the cabinet or the counter top and the wall.