I understand that there are multiple terms for the idea of how hard it is to successfully mine BTC. The terms I have seen are "difficulty", "network hashrate" and "hashrate". I am not entirely sure what the differences between these are.
On my computer, I can call SHA256 on a string. How many such input strings would I need to try right now before I would get lucky enough to successfully propose a block? And this number of tries, how is it related to "difficulty", "network hashrate" and "hashrate"?