I-joists are used for floor framing and roof rafters in residential and light commercial projects. They are comprised of LVL flanges and OSB webs, which is a very efficient use of wood fiber. I-joists are capable of longer spas than conventional lumber, easy to install due to their lightweight design, and uniform in size.
Laminated veneer lumber (LVL) is used in structural applications such as beams, headers, and hip/valley rafters. Because of how it is manufactured, it is available in lengths far beyond conventional lumber lengths, capable of carrying more load, and dimensionally stable.