Blog vs. Website
A blog is a weblog where content gets updated on a regular basis. It displays in reverse chronological order. To avoid confusion with server log, weblog was named blog. A blog is in fact one page with monthly archiving. It needs to be updated with new content periodically; otherwise, people will lose interest in it.
Definition of blog on the web
Tutorials by Jennifer [ A very interesting blog that defines blog and explains from scratch how to create your own blog ]
Whereas, a website is a collection of web pages. The first page of a website is called home page. A website has a defined domain name (address) on the world wide web. Websites basically aren't updated as often as blogs, they stand more for longer lasting information - certainly depending on their actual purpose.
Definition of website on the web
I don't want to write more about what has already been written. Thus, if you are interested in more details, please feel free to visit one of the suggested links above, or type-in "blog" or "website" in Google search!