The distinction turns on a ship's main design priority. Anti-submarine warfare defines a frigate in this framework, while patrol and visible presence shape a light frigate. Light frigates inherit much of the historical sloop role and are usually, though not universally, diesel-powered. An offshore patrol vessel may defend itself in a milder setting, but a frigate is expected to operate under greater threat. The boundaries overlap as patrol vessels grow and light-frigate missions vary.
Notable Point · 49:11-51:02
Frigate, light frigate and OPV design priorities
A role-based distinction separates ASW-led frigates, presence-oriented light frigates and lower-threat OPVs.