In telescopic opamps, the output and input common mode levels are dependant on each other. The input common mode voltage is a Vt drop (lower or higher dependent on NMOS or PMOS input) different from the output common mode voltage. This is to ensure that the input diff pair is in saturation.
In Folded cascode opamp, the input and output common mode levels are independent of each other. The output common mode level depends on the NMOS and PMOS load transistors. The input common mode level depends on the input diff pair, the tail current transistor and the load transistor.
Hence in this case both the levels can be set to the same value.