@shaini07 

Due to the current chip shortage TP Link has had to use different chips supplier for some of their hardware.   As a result, this has incremented the version number, in this case from v3.2 to v4

Fundamentally they are the same device with same specifications, however it may have a different chipset inside. 

Sorry i dont have the exact chip details, but hopefully that answers your question?   There has been a fair new other TP Link devices affected also

  @Philbert 

After doing some research found this:

1. In v3.2 the 2.4 GHz speed is upto 300mbps, whereas in v4 its upto 400 Mbps

2. In v3.2 the firmware upgrade has to be done manually, whereas in v4 its over the cloud.

3. In v3.2 you cannot mange your device without being on same network, whereas in v4 its on cloud. So you can mange from anywhere.

  @shaini07 

earlier i used c6 v3.2. it was a fantastic router and works like a charm. especially the smart connect feature. which works flawlessly. it will switch to 2.4 and 5ghz band based on the distance and flexibility. i had never faced any issue.

i bought one more c6 router with version 4. first ill tell the highlights.

pros:

1. it has 400 mbps of speed compared to 300 mbps on v3.2 (2.4ghz)

2. it has nat boost which was missing on v 3.2

3. new interface for settings through browser

4.signal is best comparing to v3.2

cons:

1. smart connect is a mess. it wont switch to 5ghz and stays on 2.4ghz even when you're 1 meter away from router. even if you turn off smart connect (keeping same ssid) router prefers to stick with 2.4ghz. for getting 5ghz again you need to turn off wifi in device and reconnect. but if you go for a distance it will again switch back to 2.4 ghz. i had the similar issue with archer c80 (now i used to it). keeping seperate ssid for 2.4 and 5ghz solves the purpose.

2. there is no option to turn off one mesh (might be will receive via future update)

  @shaini07 hi do you know what is the version of archer c6u as it is is based in c6 but i am not able to figure out whether it is v3.2 or v4

  @Devanshu90 

The latest version for C6U is what I can find is v1.

you can also find the version under the router.