John Gruber (tweet):
If your keyboard doesn’t have a dedicated Enter key, you can type the Enter key by pressing Fn-Return. That’s why some Return keys have “Enter” printed in small type above the word “Return”. If your keyboard has neither a dedicated Enter key nor an Fn modifier key, I don’t think you can type Enter.
Unfortunately, my experience is that fn-Return only works properly on Apple keyboards. On third-party ones, it just generates a Return. Similarly, the fn key is often implemented as a modifier within the keyboard, so that fn-Down Arrow will send an actual Page Down but pressing fn by itself does nothing. With an Apple keyboard, you can see on-screen that the fn and arrow keys were pressed, and you can use fn by itself to trigger Mission Control, Siri, or Dictation.
As a general rule, when they differ, Return is simply the key for typing a newline character (which, on classic Mac OS, was literally a return character, but let’s not get into that here), whereas Enter enters what you’ve already typed without adding a new line.
Previously: