One major way Nick is different is that he is the only invited guest. Gatsby sent his chauffeur to Nick's house with an actual invitation, while most of the other guests simply showed up for the party. Another major difference is that Nick attempts to find his host to thank him, while the other guests make no attempt to find or thank Gatsby. In fact, everyone else views Gatsby with suspicion; they believe he was a German spy during the war or that he killed a man. They look down on him and definitely do not want to be associated with him, though they are happy to drink his champagne and dance to his orchestra. Nick, on the other hand, doesn't assume he knows anything about Gatsby.