Now, srlinuxx at TuxMachines have avoided formally comparing Ubuntu to other distros such as openSUSE or Mandriva before because in his book it's like comparing apples to oranges, but for the sake of those searching, he will try.
Read it here
So really the big basic difference is that Ubuntu is a simplified cookie cutter distribution designed to not overwhelm the new user with choice. openSUSE on the other hand is the polar opposite offering choices for every aspect of Linux computing. openSUSE is very scalable and it can be as easy or advanced as one needs. You could install openSUSE on a dozen machines and none be the same if that was your wish, whereas install Ubuntu on a dozen machines and it would be exactly alike except some might not be able to connect to the internet.