"Build a vessel that suits the environment" is a big difference. One person can build boat that can sail across the ocean. A team can build a ship that will do it safely. People sail across the ocean on canoes.

Space ships are a whole other level of technology that we don't have but have ideas on how to build.

Starships are level where we don't know if can be built. We have ideas, but those ideas aren't possible with achievable technology. It is quite possible that not possible with any technology.