What use a pair of lips?
I think what you are looking for can be found https://en.wikipedia.org/wiki/Lips#Functions_of_the_lips and https://en.wikipedia.org/wiki/Beak#Functions pretty easily.

To summarize, lips:


Mainly useful in mammals
Food intake
Articulation
Tactile organ
Erogenous zone
Facial expressions


Beaks:


Found in birds
Feeding
Defense
Manipulation of objects
Communication
Heat exchange