Whether it's attached to real estate is not a factor in the definition of "manufactured home". The Commentary to the definition in §1003.2 states:
Definition of a manufactured home. The definition in 1003.2 refers to the Federal building code for factory-built housing established by the Department of Housing and Urban Development (HUD). The HUD code requires generally that housing be essentially ready for occupancy upon leaving the factory and being transported to a building site. Modular homes that meet all of the HUD code standards are included in the definition because they are ready for occupancy upon leaving the factory. Other factory-built homes, such as panelized and pre-cut homes, generally do not meet the HUD code because they require a significant amount of construction on site before they are ready for occupancy. Loans and applications relating to manufactured homes that do not meet the HUD code should not be identified as manufactured housing under HMDA.
If it meets this definition, it is a "manufactured home" - whether attached to real estate or not.