An op-amp is an op-amp. That you have four or two in a single package is just a convenience, but irrelevant. The op-amps don't know. You can wire them up as inverting or non-inverting amplifiers (or comparators, or integrators, ...) as you wish. Sharing VREF is also irrelevant. To the op-amp, it's just a voltage. It doesn't know what you're using it for.