Frost proof hose spigots have a recessed seal, where seal sits inside the house.

Discussion

Note the freeze proof variety can still freeze if the temperature inside the house is below freezing.
The same as freeze-proof spigot can be achieved if there is a valve inside the house, and water up to the valve drains when spigot is open. In this case, after water drains, close the spigot to limit cold air getting inside the spigot. The advantage of the freeze-proof variety is if the piping is not accessible from the inside.
The only freeze-proof way to do this inside the house - is to blow out or drain water line - if the structure is not heated in winter.
Are hose spigots required by the IRC? They were until 2006 [1] and [2]
- Some jurisdictions do require them, and anti-backflow devices with them, such as this one in Ohio - [3]

Sourcing