Foundation Material. The foundation is usually built in brick work, masonry or concrete under the base of a wall or column. This will enable to transfer the load to the soil in a uniform manner and allow the transition from the structure to the soil. It will depend on the recommendation by the structural engineer. He will select the location, width and depth of every foundation in the structure. For smaller and lightweight structures, the design will be different depending on the material and location of the structure.
Whereas modern is a static term, contemporary is a dynamic, changing term. There are fewer rules in contemporary interiors than in truly modern ones, because anything kinda goes. Of course there is still a difference between good contemporary design and bad contemporary design. And everyone has their personal taste. But in contemporary design, you are free to use color and pattern.
With no real definition for the current Modern aesthetic but using both words interchangeably to describe it as if MODERN (closest to the truth and CONTEMPORARY (the farthest from the truth) were an umbrella encompassing anything not traditional.