@saratkumar 

Hi, you can tell the hardware version here:

The wireless specifications are similar, all AX1800. 

Deco X20 V1 and V2 use HomeCare security kit. Deco X20_V3 uses HomeShield.

Then there might be software features and you could refer to this link:

Understand the Differences Among Deco Firmware Platforms

Thank you very much and best regards.