You've seen the specs. Now get a close up look at the DSi LL. Nintendo has shared official hardware pics showing each color in closed and open state. See for yourself here:

Dark Brown

Wine Red

Natural White

Look like another system to you? Aside from the fat stylus, the DSi LL really does look like a standard DSi:

DSi LL to the left, DSi to the right.

Of course, when put next to one-another, the screen differences should be obvious. Compare the sizes for yourself at Nintendo's special DSi LL page.