We know what you’re thinking. Which one’s Jack and which one’s Algernon? It's hard to keep the two characters straight. Wilde built so many echoes into their actions and dialogue that on a first read, the two men seem like the same guy. Just consider their similarities: they are well educated and well off; they are trying to get wives; they have butlers and imaginary friends.
The men also share some of the traditional protagonist’s job of driving the action – both characters work hard to secure their engagements, facing the stony judgment of Lady Bracknell. Both descend on the country – essentially in disguise – to deal with the problem of Brother Ernest. Both arrange for christenings they think will bring the happy ending of marriage. And neither of them changes very much throughout the course of the play.
Why would Wilde make Jack and Algernon so much alike? Isn’t an author supposed to make characters individuals? Not necessarily. And not in a parody, farce, or satire, all of which are genres that Wilde drew on for The Importance of Being Earnest. Wilde is making fun of the Victorian upper class, to which both Jack and Algernon belong. Making light of the obsessions and faults of the upper class through Jack and Algernon at the same time is not only funnier, but it also makes Wilde’s point that the faults are in the society, not the individual.
Throughout the play, we do see that the two characters do have individual traits, which emerge most when they bicker with each other.
Even before he knows he’s an older brother, Jack acts like an older brother. As a guardian to Cecily, he’s used to setting down rules, even guiding curriculum, as we see in the tutoring scene with Miss Prism. Jack is bossy. In the first scene, he liberally dispenses "shoulds" to Algernon. Jack has no problem giving out one piece of advice after another: one shouldn’t read a private cigarette case, shouldn’t discuss modern culture, shouldn’t talk like a dentist, etc.
Jack isn't any less dishonest than Algernon, but Jack is more serious about keeping up his air of respectability. When he finally comes out with the truth about Cecily, "who addresses me as her uncle from motives of respect that [Algernon] could not possibly appreciate" he takes pains to separate himself from Algernon, who is "hardly serious enough" (I.79-83).
Jack also has a bit of that older sibling control thing, enhanced with a tendency to get in bad moods when things don’t go his way. Wilde describes Jack's reaction as "irritable" three times in the play – when Algernon rushes him, when Lady Bracknell quizzes him on Cecily’s background, and when the same lady can’t remember his father’s first name. Jack is as willing as Algernon to humiliate himself to get what he wants – the entrance with him dressed all in mourning is priceless – but he’s less amused when things turn out badly:
This ghastly state of things is what you call Bunburying, I suppose?
Yes, and a perfectly wonderful Bunbury it is. The most wonderful Bunbury I have ever had in my life. (II.357-358)
Algernon enjoys the social game, while Jack wants results.
The men are also distinct from each other in terms of their taste in women. Jack is attracted to Gwendolen, a "sensible, intellectual girl" (I.295). Gwendolen is a sophisticated city woman, and her style and education make her desirable to Jack. So does her good name – a department in which Jack, socially speaking at least, could stand to improve. Even before Jack discovers his true origins, he has a lot to gain from marriage into the Bracknell family (though he’ll have to deal with Lady Bracknell on a continual basis.)Jack Worthing Timeline