What's an insulated bowl?

Why would I want that?

And what is a bolt-down lid?

I'm looking at the models of the Toto Drake.

Do you mean an insulated tank? The purpose of an insulated tank is to prevent sweating (accumulation of moisture on the outside) of the tank in warm, moist climates. In the old days, when each flush would empty the 5-gallon tank and five new gallons of cold water would come from below into the tank, the exterior of the tank in some climates would sweat. Today, this is less of a problem, because in a a 1.6 or 1.28 gallon per flush toilet, the whole tank doesn't empty with each flush. Therefore, the water that enters the tank mixes with what is there, reducing the chilling effect of the new water. Also, because less water comes in per flush, the water that enters has been typically in a warmer environment for a while, assuming that the toilet isn't in a heavy-use commercial setting, or some such. Consensus on here is that the insulated tank is basically unnecessary in all but the most extreme environments.

A bolt down lid is just what it says. The lid bolts down to the tank, so that it isn't easily-removed, say in a commercial or public setting where an unbolted lid could be an invitation to mischief. Again, probably not necessary for home use.

Oh, thank you so much! I get it.

My pleasure. That's why we enjoy participating in this forum.