Differences between Cera & Eisenberg

"I deemed it necessary to take to the interwebs to finally educate the masses on how to tell the difference between Jesse Eisenberg and Michael Cera:
1. Eisenberg is a native of Queens, NY. Cera is Canadian. It's just a coincidence that their voices sound so similar. It's not a geographic thing.
2. Eisenberg is the one with the curly hair. If you're ever not sure which one is in the movie you're currently watching, taking a quick peek at the top of his head will give you an answer.
4. In Zombieland, Eisenberg plays a nerdy guy who has an unlikely romance with the lovely Emma Stone.Emma Stone with Michael Cera in "Superbad" (2007).

In Superbad, Cera plays a nerdy guy whose equally nerdy best friend has an unlikely romance with the lovely Emma Stone.
5. On Arrested Development, Cera played the awkward but ultimately sweet and surprisingly well-adjusted young son of the insane Bluth family. In The Squid and the Whale, Eisenberg played the awkward but ultimately creepy and damaged son of the insane Berkman family.
6. When The Squid and the Whale hit theaters in 2005, critics called Eisenberg Hollywood's most promising young everyman actor. Two years later, critics forgot that they'd already given this title to someone and re-gifted it to Cera".
Source: www.film.com

Michael Cera as Harold in the short film "Darling Darling" (2005).

"Jesse Eisenberg (The Squid and the Whale). He was Michael Cera before Michael Cera became Michael Cera. Except after Michael Cera became Michael Cera, Jesse Eisenberg was reduced to a poor man's Michael Cera. Michael Cera must have not been available to shoot Adventureland and so Jesse Eisenberg became the Michael Cera-type producers were looking for. And now with this vast Michael Cera over-exposure, is Jesse Eisenberg reclaiming his original Michael Cera status by starring in Zombieland opposite Emma Stone, a young actress who also starred opposite the actual Michael Cera in Superbad?
Jesse Eisenberg and Amber Heard in "Zombieland" (2009).

I'm on a roll with the questions here, is there a reason why Eisenberg's Adventureland and Zombieland are similarly titled? Is Michael Cera somehow behind all this?

All that matters now is that Michael Cera finally shows us he is more than just Michael Cera in this adaptation of C.D. Payne's novel. How so? By playing a youth who revolts thanks to an Edward Norton/Brad Pitt-type alter ego that does very, very bad things that none of Cera's past characters would ever have the balls to do. (Unlike the two different actors in Fight Club, Cera plays both roles in Revolt.)

Jake Gyllenhaal & Jennifer Aniston in "The Good Girl" - Gag Reel.

Directed by Miguel Arteta (absent from the big screen since 2002's The Good Girl), the film stars Cera as a virgin (but of course!) named Nick Twisp, who falls hopelessly in love (in typical wimpy Michael Cera fashion, obviously) with a young girl named Sheeni Saunders (Portia Doubleday) while on a family vacation at a trailer park".
Source: www.huffingtonpost.com

Nerdy types who resemble Michael Cera:

Michael Cera
Why you think he’s Michael Cera:
No. 1, he is Michael Cera. Nos. 2 through 4, Michael Cera is physically negligible, a rail-thin angelic man-boy with big, earnest eyes who has probably had the same haircut since 3rd grade; he stammers when he tries to talk to women, or to almost anyone, the mark of a true sensitive high school intellectual (in movies, at least); his default expression is gape-mouthed profound bewilderment, with grace notes of adolescent stupidity and subdued teenage frustration.

Why he’s not Michael Cera: Does not apply.

Paul Dano
Age: 24 Where you’ve seen him: As the son who won’t talk in “Little Miss Sunshine”; as the preacher with pretensions who spars against Daniel Day Lewis in “There Will Be Blood”; soon in “Taking Woodstock.”
Why you think he’s Michael Cera: Thin and pale; his voice breaks when he gets excited; eerily placid.

Why he’s not Michael Cera: Michael Cera has ramrod-straight posture, Dano slouches. Default expression is more purse-mouthed than gape-mouthed; taller than Cera, with a longer neck, a more oval face; seems better predisposed for drama than comedy.

Anton Yelchin
Age: 20 Where you’ve seen him: As Chekov in the new “Star Trek” picture; as teenager Kyle Reese, future father of John Connor, in the coming “Terminator Salvation”; as the kidnapped boy in “Alpha Dog.”
Why you think he’s Michael Cera: Like Michael Cera, if cast in a World War II drama, he could easily play the young soldier who represents the death of innocence; boyish face; severely pale skin; slight in appearance; deer-in-headlight eyes.

Why he’s not Michael Cera: Rarely mugs; his delivery rests more on short bursts of misplaced overconfidence than awkward hesitation.

Jesse Eisenberg
Jesse Eisenberg at Sundance Festival on 25th January 2010.

Age: 25 Where you’ve seen him: As the leading man in “Adventureland”; as Jeff Daniels’ son in “The Squid and the Whale”; soon in the comedy “Zombieland.”
Why you think he’s Michael Cera: Like Michael Cera, his niche is Indie With Poignant Laughs.

And your first reaction is not whether he is an actor but whether he is that guy you’ve never heard of whom you agreed to friend on Facebook. His skin is translucent; his eyes are wide. His delivery is pure hesitation, followed by a spew of words.

Why he’s not Michael Cera:
More geared toward drama than comedy. His hair is generally curlier. His default expression is less panic than bemusement.
Source: www.popmatters.com

MOTTOLA:“People always ask me if I thought of Michael Cera before Jesse for the role of James, and the truth is I was a fan of Jesse’s already and he was the first person I thought of. I think Jesse, maybe because he’s a New Yorker and is more neurotic than Michael, he felt more like me. My only hesitation with Jesse was that he’d done Squid and the Whale, and there’s some overlap in the characters, but when I sat down and met with him I thought, ‘Okay, I can live with the comparison,’ because I think that’s a great movie". Source: www.visimag.com