Is the difference between npn and pnp only in the direction of the current (e-k and vice versa)?

Question

Electronics

Good afternoon, tell me, the difference between pnp and npn transistors is only that
in an npn transistor, current flows from the collector to the emitter, while
in pnp, on the contrary, from the emitter to the collector?
(I do not consider the opening of the base as a positive or negative direction to it)

Answer 1

yes - only in this.

Answer 2

On the output diagram, phototransistors are drawn - this is an open collector. I doubt very much that the diagram is drawn correctly. There should be an NPN transistor on the circuit, and there is a PNP one. So not an open collector, but an open emitter. And what then protect the diodes at the output. And how to connect the correct source of 24 volts? explain
Thank you