Basically, antyhing that isn't a post is a page :) Pages can be standalone pages like these documentation pages or they can be more complex pages listing blog posts like the Innota blog, for instance.
In addition to page type, all pages can have a different template. This combination gives a lot of flexibility yet makes adding pages easy.
Page Types
Here's a description of the different page types in Innota.
Regular Page
Regular page is probably the page type you think of when you think about pages. These are simple pages with a title and content (and a bunch of other attributes).
For instance, all of these documentation pages in Innota are created using regular pages.
Post List
Post list is a page type to list all of your blog posts in reverse chronological order. This the blog index that you probably have on your front page or at /blog.
Post lists rarely have any actual content in them, but that's also possible.
You can change the number of posts visible on a single page in site settings.
Tag List
Tag lists are just like Post lists but they list the posts tagged with a certain tag. For instance, if you open http://yoursite.innota.me/tag/cat/ you could get a page listing all of your posts tagged with cat.
Tag lists are also paginated just like post lists. You can change the number of posts visible on a single page in site settings.