Snaga seems to have been exceptionally
for an orc.
This "name" comes from their word for slave, and may therefore have been an insulting nickname. Thus the confusion between possibly two "Snaga"'s.
The first was a scout during the march with the hobbits, Merry and Pippin. It is unlikely that he survived to return to Cirith Ungol to be the second Snaga. But perhaps this sneaky fellow did manage it.
Snaga was smaller than Shagrat. Snaga used a bow, threatening Shagrat with it when Shagrat tried to force him to take a message to Lugburz through the gate where all the others of the Cirith Ungol orcs had died. Shagrat was unable to take the message himself, as he had to stay with the tower as captain, and had been knifed by Gorbag.
Snaga was probably killed by Sam in the tower of Cirith Ungol. Sam heard Snaga use a whip on Frodo (to stop his singing) and attacked before he could do a second blow, cutting off Snaga's hand, the next blow unbalancing the orc so that he fell through the trap door with a cry and a thud.
References: Two Towers: "The Uruk-hai"; Return of
the King: "Tower of Cirith Ungol"