I do think that it is often easier to classify voices based on their low notes as opposed to the passaggio location. Just because the passaggio can be shifted around and can change with volume.
Here is a really nice comparison: tenor vs. baritone. Listen to the G2 (2:48 in the video) and how resonant it sounds on the baritone compared to the tenor who even struggles a little to keep the note stable. That resonance the baritone gets down there (that "ringing", powerful tone) is just impossible for a higher voice to produce.
Pretty similar for bass vs. baritone. A bass can produce such a powerful tone on an E2 usually.