How does a jfet input operational amplifier work?

A: an operational amplifier has two input A+ and a - input feeding to a base of a transistor ideally both diodes are matched with a current source to make them equal so basically they are both balanced or virtually at the same potential increasing one potential to one will inversely effect the other.

usually these junctions are transistor base to emitter but it could that one is just a plain diode working on the exponential curve of the diodes