LYaH is one of the best programming books I've ever read and is the reason I know Haskell today.

The point is not that one is better than the other, but that they are in fact the same.

Of course the FSF's way of talking about ideology instead of focussing on the software itself is better for humans. But the definitions of what counts and free vs not and open source vs not have always been basically the same.

This article makes a pretty extreme claim (since, in fact, the OSI definition of open source and the FSF definition of free software cause the software in question to be pretty much a 100% overlap) but does not provide any sort of rationale or explanation to back up the titular claim.