The terms may be used interchangeably, but they are actually two different things.
Both are “manufactured” homes –they are built in sections in a factory, and stand in contrast to site-built or “stick” housing, which are the traditional homes.
So how do they differ?
Manufactured homes are the homes once called "mobile" homes, or earlier, "trailer homes." Relatively inexpensive, and often smaller than site-built or modular homes, they are also held to less stringent standards than the other housing types. While manufactured homes conform to HUD (Housing and Urban Development code, and are inspected, they do not have to be structurally approved by an inspector.
They are always one story high and manufactured in sections at factories. Manufactured homes, transported to the site on their own wheels and a steel chassis that stays with the home, do not have a permanent or conventional foundation.
Modular Homes Have Stricter Requirements
Modular homes, while also constructed entirely in factories, are transported to their sites on flatbed trucks.They meet strict quality-control requirements prior to delivery and are built to strict specifications.
Assembled with the use of cranes, the final product is almost indistinguishable from comparable ones built on-site and must conform to the same local, state and regional building codes as their site-built neighbors.
They must be structurally approved by building inspectors.
Modular Homes Are Built From Block Sections
Built from block sections, the houses can be of any final size,and tend to follow the same market trends as site-built houses.
And while more basic than homes built on-site, they tend to be sturdier. The foundation can be dug while the house is being constructed on site and the whole process generally takes eight-14 weeks from delivery to completion.