Ogg is the container, Vorbis is the audio codec, and colloquially people just called Vorbis-encoded audio "ogg" because of the ogg container.

Vorbis was hit-or-miss. In some cases it did better on same or lower bitrate than MP3 encoded by LAME, in some cases worse. It also suffered an entirely new category of "chirpy/tweety" artefacts similar to what MP3 exhibits at very low bitrates, but with Vorbis they showed up even at nominal bitrates during certain complex spectral patterns. I was a vocal propononent of Vorbis back when it surfaced, but soon changed stance when realizing how unreliable it was quality-wise.