While the Force and Psi-phenomena seem similar, and there are areas where they overlap (tk, telepathy etc.), imho the mechanics of how they work are very different.
With Psionics, the mind is able to manipulate the outside world. Kes concentrates on a pitcher of water, and she is able to move the object through the air to her. Her mind moves the object.
With the force, the mind of the force user manipulates the ambient Force that "surrounds" and "binds things together". When Obi-Wan wants to move a pitcher of water, he reaches out through the force, moving the object. He manipulates the force, and the force moves the object.
Another way of thinking of it in this scenerio is to think of TK as, well Telekinetics, and the Force as something akin to Magnetism: Magneto needs to manipulate the Earth's magnetic Field to move objects.
Now, as to how to describe the Force, in trek terms, I'm not sure that can work. Or, you could call it a "quantumly focused energy field with dualistic tendencies"?
_________________
"Yes, it's the Apocalypse alright. I always thought I'd have a hand in it"
Professor Farnsworth