Yeah, those both makes sense. ggml was split from llama.cpp once they realized it could be useful elsewhere, so while llama.cpp is the "main playground", it's still used by others (including llama.cpp). Doesn't mean suddenly that llama.cpp is the same as ggml, not sure why you'd believe that.
“Some of the development is currently happening in the llama.cpp and whisper.cpp repos” --https://github.com/ggml-org/ggml