Debian is one of the earliest distributions that has existed for almost two decades and spawned a lot of other distributions. One of the distributions that spawned from Debian was Ubuntu More here
When it comes to the rankings, Ubuntu currently holds the crown as the top dog. Debian once held second place but has been knocked lower recently. This is quite ironic, considering that Ubuntu was developed from Debian. Part of the reason might be because Ubuntu is more user-friendly. And the fact that it isn’t too strict when it comes to proprietary software and drivers makes it a little bit easier for people to use, especially those who are not that knowledgeable in the inner workings of Linux.
Read more: Difference Between Ubuntu and Debian | Difference Between | Ubuntu vs Debian http://www.differencebetween.net/technology/difference-between-ubuntu-vs-debian/#ixzz0WU8mB9QQ