For the lazy: * An ocean liner provides transportation between a source and a destination. Historically they were often used to transport mail, thus RMS and va

For the lazy: * An ocean liner provides transportation between a source and a destination. Historically they were often used to transport mail, thus RMS and variations (Royal Mail [Motor] Ship/Vessel; "Motor" was used when most ships were steamships. I can't find a canonical answer for "vessel" but examples tend to be small ships with short routes to islands, rather than going between continents). * A cruise ship runs around in a circle visiting tourist spots, and generally don't have to be built as strongly. Recent ocean liners operate as cruise ships for part of the year.