Compared to not using instruction pipelining. What is different?
One, the control unit is pipelined. Two, because everything is pipelined, it's busy all the time and must be able to produce at least one instruction per cycle. Third, if you have a processor capable of executing more than one instruction per cycle, the control unit must be capable of handling more than one instruction per cycle, which includes decoding multiple instructions per cycle, preloading memory containing instructions before they are needed etc.