Okay, well... "close coupled" in a 2-piece toilet only means that the tank sits on and is connected to the bowl. In the old days, they used to mount the tank to the wall, perched just above the level of the bowl; then, they would connect the tank to the bowl with a big shiny elbow pipe (a 90 bend). The water would go out the bottom of the tank, into the pipe, and then into the toilet. We have an ancient one of these by American Standard that is in a rarely-used toilet closet; the date carved in the tank is 1927.
A "close coupled" toilet, which is basically every normal 2-piece in the last 20+ years, typically has an inch or so of the flush valve protruding through the flush hole in the bottom of the tank, which is secured in place with a big nut, over which goes a rubber donut which stands on top of the water entry hole on the top of the bowl, and the whole thing is secured together with bolts. (There are a few different mounting systems out today, but the basic idea is that the water flows out the bottom of the tank directly into the top of the bowl and through the channels molded in the porcelain bowl to its various destinations.) Oddly, sometimes they say 2-piece and sometimes they say "2-piece close coupled". As far as the Toto line goes, it's the same thing. Their 2-pieces are all "close-coupled", as are any such toilets today that aren't some kind of throwback designer esoteric.
The 474 is the Vespin II, which is basically a regular Drake II with a skirt. The regular Drake II and the Vespin II use the same tank (model ST454: On the box it says "Drake II/Vespin II Tank"). The skirted toilets use, as you note, the UniFit adapter, which allows you to put the thing on a 10, 12 or 14" rough-in. An advantage of the Unifit is that you secure it to the flange and then plug the toilet into the unifit, so you can be sure you have a good, firm connection to the flange that won't leak or smell. Of course, you can do that with a regular Toto just by using the proper size or number of wax rings when you install it. The real advantage is the flexibility it gives you to have the toilet fit really well in a 10 or 14" rough-in space. It's not that hard a thing to install (done it), but it's not as fast an install as just dropping the bowl on the wax and tightening the closet bolts.
The spec sheet you put up there, by the way, is for the C
UFG toilet, meaning the Drake II 1G, the one that uses only one gallon and has a different tank than the regular Drake II. Again, the regular Drake II and the Vespin II you mentioned share the same tank, whereas the Drake II 1G uses a slightly-smaller tank. Here's the spec sheet for the regular Drake II (CST454C
EFG:
https://terrylove.com/pdf/cst454cefg-specs.pdf
See...that ST454 tank looks different than the ST453U tank that is used exclusively on the CUFG (Drake II 1G).
Come on back with any more questions...