comparator vs opamp

please explain me the difference between a comparator and an opamp based on the examples given below...

1) if my v+ is 12v and my v- is 0v, input + is 3v and input- is 2 volt, what would be the output of the comparator and of opamp??
2)if input+ is 2 volt and input- is 3v , what would be the output of camparator and of opamp??

Hi,
An op amp without any feedback is a comparator. It depends on the specification of the op amp, if it's rated rail to rail, the output high can be as high as the +ve supply voltage.

The formula is Vout=A(Vnoninverting - Vinverting)

A is the gain.

An op amp is expected to reproduce the input with a gain dependent on the feedback components. An op amp always has a negative feedback. A positive feedback would make it behave as an oscillator.

The op amp has a certain voltage compliance range that is usually 0.5v less than the +Vcc and 0.5v more than the -Vcc reference. If the result of the above formula is beyond this range, the amplitude of the output is limited to this signal. This is how a comparator works.