What is the difference between a sack and a stuff in football?

A sack is a quarterback brought down behind the line while trying to pass. A stuff — ESPN’s name for a tackle for loss against the run — is a ball carrier tackled at or behind the line of scrimmage on a running play. Edge rushers collect sacks, interior linemen collect stuffs, and a defence that does neither gives its opponent second-and-short all afternoon.

Sacks (SACK) in fullStuffs (STF) in full