Key word and Running title

Key word noun - A significant word used in indexing or cataloging.

Running title and key word are semantically related. In some cases you can use "Running title" instead a noun phrase "Key word".

Running title noun - The title (or a shortened title) of a book used as a running head.

Key word and running title are semantically related. Sometimes you can replace phrase "Key word" with "Running title", this phrases are similar.