"Literally just a friendlier name" is more-or-less the OSI's spin on the split; those remaining with the FSF were concerned about a shift of focus away from principles. (With the obvious caveat that these are generalizations about a lot of individuals.)

But in practical terms, "free software" and "open source software" as used by the FSF and the OSI describe the same set of software. Consider their respective license lists:

https://www.gnu.org/licenses/license-list.html https://opensource.org/licenses/alphabetical