Earth is a program independent of a web browser. It uses the Google Maps images and information, but more intuitively and hungrily (that is, the 3D stuff couldn't be done with the scripting a browser interprets at Maps dot Google).
In addition to the neat-o 3D view, you can have it display more information. Zoom into a city and check "restaurants" or "bars" and it'll pop up with everything in the area.