Difference between a CPU and a Core

Published on October 21, 2015

We see a number of CPU’s and a number of Cores on our computers, even with our mobile gadgets, but what do they actually mean? Why does our computer identify some of our CPU’s as dual-core processor and others as quad-core processor? And what does a core have to do with it?


AMD’s Phenom II quad-core processor die diagram


To put simply, a CPU or central processing unit is what calculates and executes the instructions of a program. It can also be referred to as the brain of a computer that performs basic arithmetic, logical, control and input/output operations.

Over the years, a CPU’s form, design and implementation have changed, but its fundamental operation remains intact. Here are a few of these operations.

  • ALU or arithmetic logic unit – allows your processor to perform arithmetic and bitwise logic operations.
  • Processor Register – gives the ALU the needed data or operands and stores it.
  • Control Unit – gathers instructions from memory and performs them through the ALU, registers, and other components.

Usually, a CPU follows steps known as the instruction cycle.

  1. Fetch – gathers instructions from the computer memory
  2. Decode – determines what instructions are to be performed
  3. Execute – Executes the instruction. This is also the stage where the user may take notice of its effect.

Most modern CPU’s are contained on an IC or integrated circuit chip together with other components like memory, microcontrollers or systems on a chip (SoC). In addition to that, some CPU’s employ a multi-core processor which is basically 2 or more CPU’s inside a single chip, intended to lessen the heat coming off of your CPU and increase speed in executing program instructions.


Core is an independent processing unit that reads and executes instructions of a program. It is basically the main component of your CPU or processor. It gathers instructions from your memory and performs them. One thing to consider is that a core is inside a CPU, and depending on its architectural design, a CPU may have multiple cores.

Multi-core processor – With the advancement of computing technology, the multi-core processor is now the norm. It is a single computing component with two or more cores. It is physically a single processor, but has multiple computing components known as “cores”. These cores will now have the capability to run multiple instructions at the same time, increasing the speed when running your programs.

Comparison Chart

Electronic circuitry within a computerElectronic circuitry within a CPU
A computer may have multiple CPU’sA CPU may have multiple cores
Follows Fetch-Decode-ExecuteFollows Fetch-Decode-Execute

CPU vs Core

What is the difference between a CPU and a core? While they both serve and act as our computer’s computing component, they do have a few differences that could further explain the speed and efficiency of your computer.

A CPU, as mentioned earlier, is what executes our program’s instructions and most are contained on a single integrated circuit chip. Within this integrated circuit is found your core, input and output management unit, and other fundamental components. Core on the other hand is the one component of a CPU that does the work. It’s the one that follows your instruction cycle such as your fetch, decode and execute sequence.

Usually a multi-cored processor is described as a faster CPU compared to your single core, but in truth, it depends on the program being executed. While most will argue that multi-core processors will perform faster, a fact that is usually true on most programs, single core processors can still beat multi-cored processors for some programs for speed. This is because there are still programs that run in serial, meaning they can only be executed by following instructions step by step and can’t be executed separately. The speed and efficiency will now rely on the core speed of your CPU.


You can refer to the video below to learn more about multi-core processors.