It specifies how cheap the t3s can be but not the difference between t2 and t3.
Pricing varies from region to region, on-demand vs. reserved instance, etc.
The general answer is they are cheaper than the same sized t2 version.
(Disclosure: I work at AWS, not posting in an official capacity)
> If the instance runs at higher CPU utilization for a prolonged period, there will be an additional charge of $0.05 per vCPU-hour.
But that (rather important detail) seems to have been omitted from the pricing page?
I'll submit some feedback to the documentation team about getting that updated.
(Disclosure: Not posting in an official capacity)
If you have an account manager or solutions architect, they can probably help you connect with the right people to ask for details, though.
(Disclosure: Still not posting in an official capacity)