Are they the same, are they related in any way (besides starting with the letter 'v')?

Each location in MD has viscosity that can range between -80 and +20. As an example, if I'm at the Gazebo of Equilibrium and it has +20 viscosity, it will cost 1 + 20 AP to move away from that location. If I'm at Plains of Liberty and it has -80 viscosity, it will cost 81 - 80 AP to move away from that scene. At minimum (barring unusual circumstances) a scene should cost 1 AP to move away from. Viscosity is lowered by 4 in a scene every time somebody moves away from that scene, and will raise back up over time.

Volition is a stat that is gained when you reduce the viscosity of a location.

You can only lower viscosity, and therefore only gain volition, in the same location every once in a while.