Durability. One of the major advantages concrete blocks hold over other construction materials is durability. Concrete does not rot or mold and is not damaged by insects or other pests. It is also fireproof, and a concrete block wall can be used as a firewall between rooms or structures.A concrete block is primarily used as a building material in the construction of walls. It is sometimes called a concrete masonry unit (CMU). A concrete block is one of several precast concrete products used in construction.A brick is building material used to make walls, pavements and other elements in masonry construction. Traditionally, the term brick referred to a unit composed of clay, but it is now used to denote any rectangular units laid in mortar.Block Masonry Residential Home. The broad use of concrete blocks, or CMUs, is not just limited to industrial buildings, foundations, or retaining walls. An increasing number of builders and homeowners are recognizing the benefits of using concrete blocks as the primary material in the construction of residential homes.A concrete block is referred to as a concrete masonry unit, or CMU, in the construction industry. Concrete blocks can be solid or hollow, with two or three cores or voids.Composition. Concrete blocks are made from cast concrete (e.g. Portland cement and aggregate, usually sand and fine gravel, for high-density blocks). Lower density blocks may use industrial wastes, such as fly ash or bottom ash, as an aggregate. Lightweight blocks can also be produced using autoclaved aerated concrete.For most practical uses in today’s construction there is no difference. Both are blocks made out of cast concrete. Cinder blocks contain fly ash as an aggregate. That being said, most concrete contains fly ash in today’s construction of concrete masonry units.