client connection does not mean a physical internet connection. it means a given connection from the website to the database. every new browser window you have opened on one page will theoretically have a new connection to the database.

and, what is the difference between what two? this thread is about the function mysql_insert_id() and nothing else -- and that function is pretty well explained in this thread and also in the PHP documentation.

you're posting a lot of questions lately that are basically answered by reading through the thread you're posting in. and the threads are all a few weeks old.