Microprocessor is General purpose, hence usually no limitation with respect to Memory, speed and space. All these can be expanded to whatever the size required. Microcontrollers are typically small in size, memory availability and speed. Processor, Memory and I/O are packed into a single board in microcontroller. One or more parameters out of Memory, speed, size, durability etc are optimized in microcontroller depending on the system in which it is used.