In the above Image 1, you see is a differential amplifier . It has a negative feedback as required.
Now take a look at figure 2 below.
Lets take a look at figure 2. Now that I have changed the opamp circuit to a positive feedback,
1) Could it still be called a differential amplifier?
2) What are the functions which could be performed by the circuit above?
3) How different are the output results achieved by it to a differential amplifier?
4) How to derive the equations for this type of a circuit?