Block/Charge

[Lotto]

Consider the following two situations:

1) Dribbler A1 contacts guard B1, with contact on B1's torso.
2) Dribbler A1 gets head and shoulders past guard B1, then contact occurs.

In both situations, if B1 has not established LGP, we have a block on B1. In both situations, if B1 does not maintain verticality, which causes the contact, we have a block (or hold or some other foul) on B1.

OK, now what if B1 establishes LGP and maintains verticality? Do we have a charge in both situations? If so, what's the point of the "greater responsibility" statement that applies to situation 2 but not situation 1?

I guess my question is, what actions by B1 will lead to a different call (or no call) in these two situations?