What is difference between normally consolidated clay and over consolidated clay?

Normally consolidated clay is soil that has not been subjected to pressures greater than its current effective stress, meaning it has not experienced significant past loading. In contrast, over-consolidated clay has been subjected to higher pressures in the past, leading to a lower current void ratio and a greater resistance to deformation. This results in over-consolidated clay having a higher strength and lower compressibility compared to normally consolidated clay. The difference in consolidation history impacts how each type of clay responds to loading and changes in moisture content.