Hello,
usually PHP interpreted executed in command line uses a different configuration comparing to Apache PHP module, including less restrictive memory limit and maximum execution time. This also allows to eliminate possible issue with browser timeout.
If you append "&" sign in command line, it means running the command in background and in most cases it will be running even if you close your shell window.
Also, When I am running the script via command line and go to index.php?op=crawl via my browser I see some stats. These are the real time stats for the script that is running via the command line, correct? I am sure this is the case, but would like confirmation.
Yes, that's right.