What is a manufactured home and how does it differ from a modular home?

Manufactured Homes
A manufactured home (also known as a mobile home) is a single or multi-sectional home built on a permanent frame, like a steel undercarriage/chassis, with a removable transportation system (hitch and wheels). The unit is permanently attached to a site-built foundation and is subject to the 1976 federal standards established by the Department of Housing and Urban Development (HUD).

While many site-built homes are constructed according to a specific building code to ensure proper design and safety, all manufactured homes are constructed in accordance with the Federal Manufactured Home Construction and Safety Standards, in effect since June 15, 1976. This building code, administered by the U.S. Department of Housing and Urban Development (HUD) and known as the HUD Code, regulates manufactured home design and construction, strength and durability, fire resistance, and energy efficiency. In the early 1990s, this building code was revised to enhance energy efficiency and ventilation standards and to improve the wind resistance of manufactured homes in areas prone to hurricane-force winds.

The only sure way to tell the difference between a Manufactured (HUD) home and a Modular (UBC/IRC Code) home is the labeling!

HUD Construction Code Label
Every manufactured home has a red and silver label certifying that it was built and inspected in compliance with the HUD Code. No manufactured home may be shipped from the factory unless it complies with the HUD Code and receives the certification label from an independent, third-party inspection agency. The HUD Construction Code label will be attached on the outside of the home on each section, and starts-off being red/reddish in color. It will always have the term Housing and Urban Development within the text. The HUD label might be hidden with siding, painted over, or might have been removed.

Modular Homes
A modular home is constructed in a factory using conventional home floor joists and delivered to a site on a trailer or flat bed truck. The delivered home may be in the form of panels that are assembled at the site, may be pre-cut and assembled on site, or may be pre-built and delivered in one piece. The home, panels or pre-cut panels are lifted from the trailer and attached to a foundation. A modular home may be single or multi-storied. Modular homes are not subject to HUD standards, but must be built to state and local Uniform Building Codes.

Factory Built Label
All Modular Homes shipped into, or built in, Colorado must be approved by the Colorado Division of Housing. Once the home has met their standards, they receive a Factory Built Label, which is to be placed under the kitchen sink. The label will note that the home was built to UBC standard, or more recently, the IRC standard. The IRC Code is simply a second generation UBC. The UBC/IRC building code should be similar to most local building codes for site-built homes.
UBC = Uniform Building Code (1997)
IRC = International Residential Code (2000)