Courtesy: ConflictX    

Nuke boats S3 and S4 together.

First full view of S4 SSBNs.

The submarine is 20 metres longer has 8 launch tubes instead of 4.

Four boats of this Arihant-class are planned. The first boat of the class, INS Arihant, was commissioned in August 2016. The first four vessels are expected to be commissioned by 2025. In December 2014, the work on a second nuclear reactor began and the second boat, INS Arighat whose sea trials which started in 2017, is now completed and is scheduled to be commissioned in August, 2022 along with INS Vikrant. The final two boats INS Aridhaman (S4) and S4* (codename) in the class are expected to be larger, displacing over 1,000 tons more than the Arihant and have 8 missile launch tubes to carry up to 8 K4 or K5 and a more powerful pressurized water reactor than INS Arihant. INS Aridhaman was launched in November 2021 and expected to be commission in 2024.

Here is the original unaltered image of the Submarines by ConflictX: