Microprocessor:

A Microprocessor is a general-purpose digital computer central processing unit. To make a complete microcomputer, you add memory (ROM and RAM) memory decoders, an oscillator, and a number of I/O devices.

The prime use of a microprocessor is to read data, perform extensive calculations on that data, and store the results in a mass storage device or display the results. The design of the microcontroller is driven by the desire to make it as expandable and flexible as possible.

Microcontrollers:

A Microcontroller is a true computer on a chip. The design incorporates all of the features found in a micro-processor CPU: ALU, PC, SP, and registers. It also has ROM, RAM, parallel I/O, serial I/O, counters and a clock circuit.

The Microcontroller is a general-purpose device meant to read data, perform limited calculations on that data and control its environment based on those calculations.

The prime use of a Microcontroller is to control the operations of a machine using a fixed program that is stored in ROM and does not change over the lifetime of the system. The Microcontroller is concerned with getting data from and to its own pins; the architecture and instruction set are optimized to handle data in bit and byte size.