Being a Linux admin user I have always used both sudo and su. As a system admin, it is very important for you to know the difference between two. For those who do not have basic idea about the difference between these two or are always confused between the two, here is a list of 13 Q&A that are aimed to make you understand the intricacies of both sudo and su. Towards the end, I have linked some good discussion on web related to different options of sudo and su.
NOTE – This article is specific to Ubuntu only. Though some information might be applicable to most of the popular Linux distributions.