The T3S is a bottom coil clearomizer. That's why you can't see the wicks as easily as in the second picture. In the first picture of the T3S, if you look all the way at the bottom of the clear tank (right below where it says .4ml) you'll see a little bit of the wick poking out.
As the name implies, the removable atomizer head and wicks are in the
bottom of the TS3, while in the other picture it's at the
top.
As far as vaping experience goes, the main differences are that top coil clearomizers will give you a warmer vape and they're easier to fill (because you just unscrew the top). With the bottom coil clearomizers you'll get a cooler vape, and it's a little more annoying to fill, BUT there's less of a chance of getting dry hits. (This is because... well, gravity is a thing.)
I hope any of that made sense to you.

If not, just ask. Most people on this forum are extremely helpful and supportive.