Corvettes, sloops, and build standards

Can small Buff-class vessels be called corvettes, or are they sloops?

The distinction is not simply tonnage: sloops are built to naval standards, corvettes to civilian standards, with frigates in between.

The difference between a corvette and a sloop is whether the vessel is built to full naval standards or civilian or Merchant Marine standards, with frigates occupying a middle ground. Wartime escort categories therefore cannot be reduced to tonnage. The distinction gives Royal Navy type labels more precision.