There are 2 types of bricks that we commonly see when we pass by some construction site. One is the cement block bricks and the other is the red clay bricks. Both are equally strong if manufactured according to specifications. The only difference is red bricks are more fire resistant.
It is normal practice to use red bricks for walls partitioning among link houses, that is the common wall between two houses linked together. This will protect the adjoining house if an unfortunate incident of fire happens. The cement bricks are used for partitioning the walls of rooms inside the house itself. The difference in prices, if calculated on per brick basis does not differ much, but when the housing project is enormous, then the developers does saves considerably.
Having said that, it is not the bricks that is the most important aspect of a house. The most important aspect is the structure and the foundation. If the main skeleton structure is good and strong, you can theoretically use sheets of plywood as walls and the house will not crumble on you. So when you see houses built with cement bricks, don’t jump to conclusions that the house is not strong.
Another popular kind of bricks that was very popular many years ago was the hollow slab bricks. It comes in sizes twice the size of a regular brick. Most low cost houses built many years ago uses this hollow blocks as walls and till today they are still standing. I don’t the real reason for this block’s natural death, but is does makes installation of wiring and plumbing systems very difficult. Because it is hollow it is almost impossible to get a good fixture of anything on the walls. Maybe that is the reason why people stopped using these hollow blocks altogether.