What's the difference between 7/11 and 9/11?

The joke “What’s the difference between 7/11 and 9/11? One is a part-time job, the other an inside job” plays on the similarity between the numbers “7/11” and “9/11,” but it deals with two very different and sensitive topics. 7/11 refers to the convenience store chain, which is often associated with part-time employment. 9/11 refers to the September 11, 2001, terrorist attacks in the United States. The phrase “inside job” is a conspiracy theory suggesting that the U.S. government was involved in the attacks. The joke attempts to create humor through the juxtaposition of a mundane topic (part-time jobs) with a serious and tragic event (9/11).