Inline frames are used to embed "plugins" into parts of a page. Seen google maps on a website before? Those are iframes.
Actual frames on the other hand are quite pointless. They're virtually never used in professional websites. If you ever go to a high school you may see IT projects that use frames for "navigation bars" or something. They take up half the page (or however you configure it) and are loaded as a separate page.
Simply put: iframes can be used as plugins. Frames are inelegant and not very useful
Edit:
To be more specific, iframes and frames are quite different.
Using my google maps example, and iframe would should a little box on the page as you're use to it. A plain frame would take half the screen to display (you can set up many frames so that a particular frame is in the middle of the screen, but why do that when you can use an inline frame?)
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
