Web 1.0 and 2.0 refer to a general evolution of websites and applications that is occurring on the internet. Whereas web pages were once static, they are now very dynamic. For example: The Web 1.0...
The basic difference is that Web 2.0 is dynamic where you can interact with website (comments, input, etc.) and Web 1.0 was just static websites where you couldn't really interact with websites...
source of the content: 1.0 web site owner generated or 2.0 content is generated by the web site visitors/surfers (making it much easier to fill the site with relevant content, e.g. answers.com)