That's right. Open Source typically means OSI approved license. Sadly, Open Source gets used as a term to refer to things that are inclusive in some way, or where access to source code is given without the bundle of rights associated with OSI approved licenses.

As RMS says, all Free Software is open source. I believe the converse statement to be true always or nearly always all the time. Though the licenses are the same, the guiding philosophies are different. Open Source tends to focus on the benefits of openness, such as quality resulting from many reviewers. By contrast, RMS and the Free software folks will tell you that quality isn't the primary aim--the 4 freedoms are.

In terms of licenses, Copyleft licenses are a subset of Free and Open Source licenses that restrict the ability to make derived works non-Free/Open. E.g. BSD is Free software, but not Copyleft.