Even though there's no technical definition of "site", I don't believe you can conduct a clear analysis of search results without knowing the terms for the different types of sites themselves.
Authority Site - A site that may or may not have Google's trust (hey there's another term to add), but does have respect and trust from the peers within it's niche (whoops, another one).
Scraper Site - A site that develops little unique content on it's own, but rather obtains it content from already published articles and items on other sites.
MFA Site - A "Made for Adsense" site. A site that was created for the sole purpose of getting visitors to click ads. These sites offer very little content, but numerous ads. Because there are arguments that all sites with Adsense on them are MFA's, this term is used in it's strictest since when referring to MFA sites.
Directory Site - A site that organizes items (for example, url's) so that visitors may easily find them.
Thin Site - Usually an affiliate based site. It may contain content, but the content could be from the affiliate itself.