The key point in the federal definition of a "manufactured home" is that it is a house constructed in a factory rather than built on a lot. Some federal statutes still refer to "mobile homes", but "manufactured home" is the newer term.
If a mobile home is 40 feet long or greater than 8 feet wide, it is probably a “manufactured home” for purposes of federal law.
All manufactured and mobile homes must meet the federal safety standards referenced below.