In the gemara in Bava Kama on Daf 3b there is a discussion about what the word Maveh (מבעה) in the Mishnah [on 2a] means. The gemara brings a dispute: Rav holds that Maveh means "man" (i.e. when a man damages) and Shmuel holds Maveh means "tooth" (i.e. when an animal damages by eating).
The Rabbeinu Chananel on that daf says: [in the print I linked to, it's on the right side, 16 lines from the end]
וקיימא לן כרב דסוגיין דשמעתין כותיה
That we pasken like Rav [...]
My question is what practical difference does this make? At the end of the day both Rav and Shmuel agree that an animal and and a man who damage are obligated to pay. They are only arguing about what the word in the Mishnah means.
So why does the Rabeinu Chananel say that we Pasken like Rav? What is this coming to teach us?