The other thing that is unique to the T420 model is the noise-canceling functions that can either block the ambient noise, or the keyboard noise. If you’ve been conferencing often enough, you know how annoying it is to hear someone typing heavily on the call :)
As it is the case with other Lenovo computers, the T420 should boot in 30 seconds (at least when it’s new and clean), thanks to the Lenovo Enhanced Experience and optimizations that Lenovo did to its Windows installation.