Is FIOSS the same as modular?

While FIOSS and modular are both off-site construction methods that reduce build cycle time, they employ different approaches. 

FIOSS incorporates panelization, which involves manufacturing the critical structural elements in panels that, after delivery to the job site, precisely fit together to create an weather-tight supershell.

Modular involves building a structure in box-like sections – or modules – that are pre-plumbed and pre-wired before delivery to site for assembly.

In general, it is easier and more cost effective to ship to job sites prefabricated panels as opposed to modules, as the panels can be stacked on top of one another.