DA has the functionality to change the basic look of windows, but it dosen't add any new features. all it does is get all the options already in windows and it combines them into one program.
(1) Window Blinds is able to change the entire look of the UI, for a bit of a look at what it can do, just look at a screenshot on this page, or go to https://www.stardock.com and there's a few good screenshots there.
Desktop X can change how your desktop looks and functions; you can put real objects on your desktop, instead of just normal icons.
Object Bar can change how your start menu works; eg. if you have Windows 98, you can make your taskbar look and work like the taskbar from XP, if you have XP, you can change it to look like the tasskbar from 98 (you can do that anyway, but that's just a demonstration), or you can turn it into Mac OS, Linux, BeOS, every other OS existing, or something completely original.
those are the main programs that i use, so i can't really comment on what other programs can do.
(2) Window Blinds can change how the entire thing looks, not just whether the buttons are normal or inverted, and it dosen't just give you a choice of 2 colours to use in the title bars (which is a basic windows function anyway)
(3) I'm pretty sure there's good instructions somewhere, but i wouldn't have a clue, because the program is pretty much self-explainatory, and the things you don't understand, you can ask for help on this message board and you'll get help, as long as the question makes sense.
(4) Window Blinds dosen't change the icons (but there's other programs on this site that do), and it dosen't change the background, screensavers or anything like that.
WB isn't really anything like DA, the only thing the same is how it can change the look of windows, but it does it in a completely different way.
I have used both programs, and DA didn't really do anything i couldn't already do with my computer, while WB can make your computer look like anything at all.
When it's used with other Stardock apps, you can make your entire computer look like a Mac, Linux, BeOS, Win XP, Win 3.11 (don't ask me why you'd want to, but like i've said, anything is possible), you can make it look like people's interpretations of the upcoming windows version (blackcomb i think it's called), or you can make it look like anything you want it to.
i think that about does it. and no, i'm not a stardock employee, but i love the programs they make.
i hope this helps you.