Commission as a term is used to refer to the institution as a whole. Interchangeably, it is also used to refer to its two components: the College of Commissioners and the permanent services, which can be confusing (Corbett, Peterson, Bomberg, 2012, p. 49). See below their main differences and how to distinguish them.
To better understand this distinction watch this video (BBC, 2012).
What is on the 13th floor of the Commission’s building?
How many civil servants are there?