Diese Kopfhörer funktionieren nicht.

English Translation

These earphones don’t work.

Kopfhörer = headphones
Ohrhörer = earphones

There are multiple things to say about this:

  1. There are lots of edits, links and unlinks on tatoeba for these sentences.
  2. There is also an english variant that uses “headphones” in the same list of sentences.
  3. I think many people use the word “Kopfhörer” as a generalization that also includes earphones, not just over-the-ear with headband.
  4. In english, there’s also the term “in-ear headphones”, so the generalization seems similar.

Literally, the correspondence is obviously as you said, but in practical usage the borders are a lot more blurry.

Also: In german, the over-the-ear variety is usually “der Kopfhörer”, i.e. singular. If you use it in the plural like that, it can quite possibly refer to in-ears (or more than one set of headphones of course).