What is "Cumulative Update" ?

Hi Mridu, 

Thank you for posting your query on Microsoft Community.

As per your query, I like to inform you that;

1) Cumulative updates are the Windows updates, which includes improvements to enhance the functionality of the application/programs on Windows Operating system.

2) Windows Update (or Microsoft Update) utility is used to keep your Windows-based computer up-to-date with the latest patches.

For any query related to Windows Operating System, feel free to post on Microsoft Community.

To be honest, that answer doesn't really answer the question, since the question clearly asked the difference between simple update and cumulative update. I think JimWynne answer is more correct to answer this question.

In term of quantity:

Simple update is just a single update which fix a problem.

Cumulative update is an update which includes previously released updates, it's like more than one simple update bundled together. For example if Microsoft release update KB00001 in July, KB00002 in August, and KB00003 in September. If Microsoft release cumulative update KB00004 which basically packed KB00001, KB00002, and KB0003 together, after you install cumulative update KB00004 you wouldn't need to install previously released KB00001, KB00002, or KB00003 anymore.

What is main difference between simple updates and cumulative ones ?