In short: It's not an inherent or technical difference so much as an ecosystem difference. Win8 developers think about Live Tiles differently than Android developers do about widgets. (Right?)
The non-discrete page-flipping (so you can scroll one column at a time, instead of a whole screen) is nice. I don't know any Android launcher that can do that.
This one can:
https://play.google.com/store/apps/details?id=net.pierrox.li...
With Lightning Launcher, you can also skip the grid altogether and freely align, scale and even rotate your widgets and zoom in and out in the launcher, if you want. It's very customizable.
Live Tiles are consistent, with only three square (rectangular) sizes to pick from. The fluid scrolling through them (rather than page by page) makes it feel more spacious. I have an entire home page dedicated to Facebook, for example, because the Facebook widget that shows me updates (and only one update at a time) takes up fully half the screen. The weather widget I use takes an entire line of icons, and the calendar widget takes up two columns by three rows. It's like playing a jigsaw puzzle trying to arrange a useful "live" home screen. Live Tiles are also visually consistent, which Android widgets are not (my Android home screen looks hideous).
A Live Tile is a app shortcut that also acts as a widget by displaying useful information. An Android widget is a widget that can also link to the application. That tiny difference is a huge gap in comparison.