Main Difference

A computer completes when many components come together to form a device, each one of them has own significance and the way they make things happen. The two most important parts getting discussed in this article are CPU and ALU, they get known as Central Processing Unit and the Arithmetic Logic Unit. The first one is responsible for all the activities that go on in a device and then referred to as the heart of the computer. While the other one is in charge of the logical and mathematical operations that occur within the system and makes certain instruction complete in the correct manner.

ALU vs. CPU — Is There a Difference?

Difference Between ALU and CPU


The full name of ALU is Arithmetic Logic Unit, and the full name of CPU is Central Processing Unit.


The primary task of ALU is to perform all the operations that relate to human logic and mathematics whereas the main function of central processing unit is to make sure all the functions are performed accurately on time.


An arithmetic logic unit is part of central processing unit.


There can be one or more central processing units in a computer depending on the requirement, but there is only one


arithmetic logic unit in a central processing unit.


A CPU also was known as a processor, interprets and carries out the basic instructions that operate a computer. An ALU performs basic calculations such as addition, subtraction, multiplication, and division.



Central parts of ALU include an arithmetic unit and logical unit whereas the main parts of CPU include arithmetic logic unit, floating point unit, register that holds all the instructions and L1 and L2 cache memory.


(computer science) the part of a computer (a microprocessor chip) that does most of the data processing; the CPU and the memory form the central part of a computer to which the peripherals are attached

Comparison Chart

Arithmetic Logic Unit Central Processing Unit
Arithmetic Unit and Logic Unit Monitor, Microcontroller, Microprocessor, Memory, etc.
Performs basic calculations such as addition, subtraction, multiplication, and division. Interprets and carries out the basic instructions that operate a computer.
perform all the operations that relate to human logic and mathematics. Make sure all the functions are performed accurately on time.
Central part of the CPU Central part of the computer

Definition of ALU

ALU which is more broadly called the Arithmetic Logic Unit is the primary component of the central processing unit. The chief job of this unit is to perform all the logical arithmetic operations, such as addition, subtraction, multiplication, division, and many others. It is regarded as the most dominant part of the CPU, and many of the original functions will seize to work without it. In most of the modern computers, it gets divided into two more parts; the first one is the AU, that deals with the arithmetic operations such as the ones mentioned above and the second one is the LU, known as a logical unit that deals with the logical operations that define the subject. Many computers have more than one such unit and deal with the fixed point operations and the floating point operations at the same time. In the computers used at homes, most of the times this process has a proper chip called the numeric coprocessor. The data that comes along its way is direct, and so are the instructions implemented. Input is usually the instruction word that contains an operation mode, more than one operands and sometimes a format code is also present along. The output, in this case, consists of a result that is placed in a storage register and has specific settings that indicate that the action carried out successfully. A separate storage space is present within the system and has several other features such as giving negative values, performing operations on the numbers that do not compliment with the logic and many others.

Definition of CPU

CPU is the most important part of the computer and is known by many names such as a processor, microprocessor, central processor and others. It is the logical circuit that acts on the several activities going on within the device and gets termed as the heart of the computer. The steps involved are same as the process mentioned above where the instruction that fetches from the memory unit, then it is decoded to make it understandable for the computer, reading the instruction and then executing it becomes the next part. The essential elements that become part of the processor are the arithmetic logic unit that performs all the arithmetic and logic operations, floating point unit known as the math coprocessor. The next part is called a register that holds all the instructions and other data and supplies them to the system whenever it is required. The last two parts are the L1 and L2 cache memory where their inclusion in the CPU saves time, and the data does not have to be input again and again. Most of the systems that exist in today’s world have more than two processors to enhance the performance. This action helps in a way that when the computer has to work at faster speeds, although these are two separate processors, combining them in the same socket makes then work at second speeds. For a personal computer, this term gets used for a processing element contained within the single integrated circuitry called the IC chip. Most important providers of such processors are known as Intel and AMD.


We get to hear about these terms a lot in our daily routines, and therefore this article clears all the primary functions, their working and examples to make sure everything becomes simplified for the reader and they get to know more about a central processing unit and arithmetic logic unit.