What's the difference bettween Office 2021 and office 2021 LTSC

Microsoft Office 2021 and Microsoft Office LTSC 2021 are both versions of Microsoft's productivity software, but they are separate and have different licensing agreements: 

Office 2021

Office 2021 is a standalone version of Microsoft's Office suite of applications for Windows and macOS. It was released on October 5, 2021 and includes the core Office applications, Word, Excel, and PowerPoint, plus other tools. It is One-time purchases are available for both PCs and Macs. However, there are no upgrade options, which means if you plan to upgrade to the next major release, you'll have to buy it at full price.

Office LTSC 2021

Office LTSC 2021 is the latest version of Microsoft's productivity software that's available to organizations through a volume licensing agreement and is a perpetually licensed version of Microsoft Office. It's available for commercial and government customers on both Windows and Mac and includes Word, Excel, PowerPoint, Outlook, OneNote, Access (Windows only), and Publisher (Windows only). Office LTSC 2021 is updated about once a month, usually on the second Tuesday of the month, but it doesn't receive new features after it's released. Microsoft supports each LTSC release for five years !

Download and Install

Office 2021

You can download and install the Office 2021 at www.office.com/setup online , or download the Official file such as :
officecdn.microsoft.com/pr/492350f6-3a01-4f97-b9c0-c7c6ddf67d60/media/en-US/ProPlus2021Retail.img 

Office 2021 LTSC

You need to download and install the office 2021 LTSC from  https://learn.microsoft.com/en-us/office/ltsc/2021/deploy

License 

Office LTSC 2021 (volume licensed) and Office 2021 (retail Licensed)

Activaton :

Office LTSC 2021 need a Volume key to activate , office 2021 need a retail key to activate, 

and you can get both from the Microsoft partner store Keyingo.com