Difference of Open Source v Closed Source

Difference between Open Source v Closed Source

Can someone please tell me what is the difference between these two but in TECHNICAL detail. I’v searched and seen videos but none of them go to great detail or technical detail.

What I want to know is whats the core underlying of the two what differentiates one from the other. Like do the files are present in the Open Source and not present on the closed one. If thats so, why cant hackers just get the source files or source code. Or even jailbreakers. Why cant they do it, since they can tweak the system anyway they want?!

Is there a kind of “jailbreak” or hack that could make these file or lines of code public or available.

Like a programmer how do you go about to differentiate the two at the core technically what you do find in one that you dont find in the other.

I hope I’m clear.

Thank you