The stars and gas that comprise the tails will have been pulled from the easily distorted galactic discs (or other extremities) of one or both bodies, rather than the gravitationally bound galactic centers. Two very prominent examples of collisions producing tidal tails are the Mice Galaxies and the Antennae Galaxies.
The stars and gas that comprise the tails will have been pulled from the easily warped outer regions (or other extensions) of one or both bodies, as opposed to their gravitationally bound core. Two prominent cases of collisions producing tidal tails are the Mice Galaxies and the Antennae Galaxies.