Refractory bricks, also called fire bricks, are used in building an oven for personal (home) use because of their ability to withstand high heats. The bricks absorb the heat very well, have a very good thermal conductivity, which makes them ideal for extended use. If you will use a good quality of fire bricks, it will keep the oven hot for a longer period of time without dissipating the heat out. Refractory bricks can be used for a long period of time because of its quality. Regular bricks is not a good material in building a pizza oven because it cannot withstand heat so it will crack.