T2 vs T3 Instance type

A customer wants to migrate their T2 instances types to the respective T3 type. Majority of their instances were launched in 2019 but some were launched in 2018 and other in 2020. They want to know what is the significant architectural difference between T2 and T3. They have some third party software running on these instances which ties the licensing with mac address and thus want to know the architectural difference between the two type as well as T2 launched in 2018 vs T2 launched in 2020 and what they have to consider when moving all of them to current T3. Beside T2 they also want to do the migration from m4 to m5 and c4 to c5 and all of the m4 and c4 were launched in 2019.

I would really appreciate if someone can point me in the right direction.