An inline frame is a box within a page and if you click a link in the main page its content changes.
There's a good overview and tutorial at the following link:
A normal frameset is two or more web pages displayed as one. Click a link in one and one of the others changes.
An overview on a normal frameset is at this link:
I don't much like frames in general. They look nice enough but there are a lot of issues to overcome with them regarding search engines, ensuring page loads and all kinds of other things and it can be a bit inconvenient at times.