When installing raspian via NOOBS the following repository can be found in
deb http://raspbian.raspberrypi.org/raspbian/ stretch main contrib non-free rpi
But there are a lot of packages "missing" that I frequently use. On a different raspberry pi that I upgraded from an older version of Raspbian the source repository is:
deb http://mirrordirector.raspbian.org/raspbian/ stretch main contrib non-free rpi
What is the differences between those two?