What is the Difference Between Solid or Engineered Wood Flooring?

Both solid and engineered wood floors are made using real wood,
so both are environmentally friendly.  
 
Solid Wood Floor

Solid wood flooring is exactly what the name implies: a solid piece of wood from top to bottom. The thickness of solid wood flooring can vary, but generally ranges from 3/4” to 5/16”. Solid wood can be used in any room that is above grade (above ground). One of the many benefits of solid wood flooring is that it can be sanded and refinished many times.  Solid wood floors are ideal in family/living rooms, dining rooms, bedrooms, and even kitchens and powder rooms. About the only place you can’t use solid wood flooring is in the basement, but there’s a solution for that area too.  
 

 Engineered Wood Flooring

Engineered wood floors are real wood floors that are manufactured using multiple layers of wood veneers.  The layers that you can’t see can be of the same species, or of different species. The grain of each layer runs in perpendicular directions, which makes it very dimensionally stable. This means that the wood will expand and contract less than solid wood flooring during fluctuations in humidity and temperature. 

Engineered floors can be nailed or stapled to a wood subfloor, or glued down to a wood or concrete subfloor. This makes engineered wood floors ideal for slab and basement installations, but they can be used in any room above, on or below grade. While this type of flooring can be sanded and refinished, it cannot be done as many times as solid wood flooring.

Source:  National Wood Flooring Association