is it a large house or a mansion
English (language) A castle is a fortress. It may also have a residence, and many castles were residences of various lords and nobles, but a castle isn't required to be a residence, as many were built to be forts guarding militarily interesting areas. A mansion is a large, opulent residence. It may have a fairly high degree of security and some level of fortification to protect the people living there, but it is not intended to be a strong place with strategic military importance. Written Jun 12, 2015 â¢ View Upvotes.