The android Browser is not the Chrome Browser, it can't even fully sync with it. These are two totally different developer Teams within Google and they don't share code much, as they have admitted themselves. Also, there are no known Plans from Google on merging the two OSes right now. I also don't think that would be a wise decision.
So to answer the question: these are two totally different operating systems with totally different concepts.
@Ronaldst Google has stated there are no such plans to merge the OS's.
Also to answer the original question Chrome OS is very different from Android. Android uses local apps. Chrome focuses on web apps.
Android is focused on tablets and cellphones.
Chrome OS is aimed at Laptops, Netbooks, Tablets, and eventually PC's(there is a PC coming out but Google has stated they don't expect to make the PC market their main focus for a long time if ever).
Chrome OS (as a part of Google's tactic to NOT re-invent the wheel) is based off of Gentoo Linux, a mildly popular distribution of Linux. It has most everything ripped out (you barely have a command-line text-editor) for speed and performance.