On a ship with two lifeboats both lifeboats are identical, except one is marked “RESCUE” on the outside.
The difference (at least on the ships I was on) is the davits for #1 boat, the designated rescue boat had a bigger winch motor and the winch had two speeds. The faster speed was to recover the boat in rough seas.
The other difference was the rescue boat was equipped with “lifeboat recovery strops”.
