PHP sites
This site is a pure PHP site, which uses code functionality to more rapidly develop modules of code. For example each page has a header which is common code used for all pages. This is simplistic coding at the most basic level with PHP, it does not employ a framework or even Object Oriented modules. Sometimes, simple is best.
Ajax sites
Using Javascript, the PHP site is extended to make a simple SPA, in one page load, multiple views can be supported by reloading a frame using Ajax calls to collect content. An even more simple application is build using many HTML snippets, little slices of content that are gotten from the file system and served as part of the page. A framework in its most basic form. Make a very fast and easy to maintain site when content is delivered in small chunks which is often the case.