How to differentiate between click (and release) button and press (and hold) button

1. What is the difference between press and click?
2. What is the hold button?

What is the difference between press and click?

In answer to your question: the difference between click and press is that click evokes the audible (and perhaps even tangible) feedback from the mouse, whereas press simply refers to the generic action of pushing the button.

What is the hold button?

noun. a button on a telephone that enables someone to interrupt an incoming call temporarily in order to answer another call.