Neither of these two characters is truly engaged with reality. This is one significant similarity connecting Jay Gatsby and George Wilson.
These men both present examples of characters dedicated to a vision (even if that vision is illusory) and who fail to see the reality of the world around them, the reality that other people live within.
Gatsby's vision is one of romance and ambition.
His ill-gotten wealth is acquired solely to gain acceptance into the sophisticated, moneyed world of the woman he loves, Daisy Fay Buchanan.
When told that repeating the past is impossible, Gatsby replies to the contrary, insisting that his vision is achievable.
This obsession is characteristic of a dreamer like Gatsby, who loses a sense of reality but rather believes in “a promise that the rock of the world was founded securely on a fairy's wing.”
Though George Wilson is not the kind of romantic or dreamer than Gatsby is, Wilson is equally distant from the world of others. He fails to recognize his wife's affair until it is too late. He imagines that the billboard near his garage features God, not a doctor.
As he grieves, he looks out the window at the eyes of Dr. T. J. Eckleburg. He remembers telling Myrtle, “God knows what you’ve been doing.” Still looking at the billboard, he also recalls warning, “God sees everything.” Seeing George’s eyes fixed on the billboard, Michaelis simplistically reminds him, “That’s an advertisement.”
Wilson broods and, depressed, becomes convinced that he is acting within a divine or divinely-arbitrated situation.
Wilson ties his fate to Gatsby's when he acts upon another illusion. Wilson is led to believe that Gatsby was driving the car that killed Myrtle Wilson. Wilson tracks down Gatsby, with Tom's help, and kills him.
The two men, living in realities of their own, collide fatally. We might argue that if these two men were less dedicated to their respective fantasies, there would have been no murder. (Gatsby would have acted to protect himself. Wilson would have checked on the facts of the situation.)
On the surface Gatsby and Wilson are opposites: in contrast to Gatsby, Wilson is impoverished running an unsuccessful garage. Also, while Gatsby possesses immense physical and personal charm, Wilson is 'spiritless..anaemic' although 'faintly handsome'.
However, there is a link in their relationship to the truly wealthy people of East Egg. They both view them from afar: Gatsby views them and Daisy's green light across the bay from his home in West Egg. Wilson views them and their rich cars only as they stop at his petrol station on their way into New York. Neither Gatsby or Wilson belong to this class although they have plenty of contact with it.
Tom Buchanan does belong to this class and he destroys both of them. Having first had an affair with the wife he adores, he gives Wilson the false information that Gatsby,not Daisy, drove the car that knocked her down. This signs both men's death warrant; when Nick writes, 'They were careless people, Tom and Daisy - they smashed up things and creatures and then retreated back into their money' the reader thinks of what they have done to Gatsby and Wilson.
Also both Gatsby and Wilson dedicate their lives to a single woman. Gatsby's pursuit of wealth is only the means to an end: Daisy. When Myrtle is killed Wilson kills the man he thinks responsible (ironically Gatsby) and then kills himself. He has no wish to live having lost her. Perhaps Gatsby too has no wish to live having lost Daisy.