[gmx-users] difference between Pulling and Acceleration?

[Tom]

Dear Gromacs Developer,

In the version of 5.0 or later, Gromacs has the functionalities
of Non-equilibrium MD by assigning the group of acceleration.

I am confused what is the difference between this acceleration
and the previous functionality of Non-equilibrium Pulling.

Pulling is to pull the group center of mass.
Does NEMD/acceleration assign acceleration of each atoms (not
center of mass) inside the group, like some external field of gravity ?

Thanks a lot for the information!

Thomas