In “Get Him To the Greek,” opening June 4, Jonah Hill (“Superbad”) plays the awkward, music-loving Aaron Green, an employee of a major recording company. When his boss sends him to meet rebellious, free-wheeling rockstar-turned-junkie Aldous Snow (Russel Brand) Aaron is nowhere near prepared for the wild hijinks that ensue. He has 72 hours to get Snow from his penthouse in London to the Greek Theater in L.A., but Snow is not going quietly.

Snow has appeared on the silver screen before, in “Forgetting Sarah Marshall,” where Brand played the hippie pop-singer who steals away the protagonist’s dream girl. However, despite marked similarities, the happy, free-wheeling Aldous Snow from “Sarah Marshall” is nowhere near as wild or self-destructive as the character in “Greek.”

“‘Forgetting Sarah Marshall’ was a laugh because it was all about restraint,” said Brand. “For a supporting role I had to be kind of measured and gentle; the key thing for me was making a sympathetic villain, a character [whose] function was to antagonize the protagonist, to fuck him off because I’ve got his bird. But in this film the character’s back on drugs, the arc is built around his conduct and his behavior and it’s sort of a double-act with Jonah. I had a lot more room to explore that darkness and to show off.”

Although Brand is reprising his role, Hill, who also had a supporting role in “Forgetting Sarah Marshall,” has embraced the chance to change roles. Instead of resurrecting his character from “Sarah Marshall”—a silly, slightly manic waiter—Hill went back to the drawing board for the mild-mannered Aaron Green.

“My character in ‘Sarah Marshall’ wouldn’t have been interesting to see throughout a whole movie,” Hill explained, “He was sort of... one-dimensional. He was more the funny, weird stalker-ish guy. Aaron’s probably the most together character I’ve ever played in a film... I just felt like Matthew the waiter is a weird character, but he’s not someone you might want to sit through a whole film [with], you might not buy it.”

Off screen, both men are very involved in comedy and performance of all kinds. Hill began his career performing in one-act plays in New York City, and now alternates between acting, writing, and producing. Between acting gigs, he has recently helped to write and produce “Brüno” for Sacha Baron Cohen, and soon will be writing and producing the film adaptation of “21 Jump Street.”

“If this wasn’t my job I would be doing this anyways for free,” he said.  “My advice to anyone is sit down and write, get some friends, borrow a camera, borrow whatever and don’t make it fancy, just trial and error. Just make little films. That’s what I’d be doing in my apartment if I wasn’t doing this. Just find what you love and work your ass off at it.”

Brand is also involved in comedy, performing stand-up sketches and writing books. Although he is decidedly British, Brand has found a niche in American pop culture.

“I’ve been observing you Americans on a Petri dish... There are some distinctions but I think that both countries are interested in manners and protocol. You know British people are thought of as being incredibly polite and it’s true. I suppose that you don’t have such a vindictive media. I think that there is social mobility, a spirit where achieving is a positive thing.”

“But then again,” he added, “you have no football here. Except that thing where you touch it with your hands and call it football. I’m still mad about that.”

Hill’s vision of comedy stems from  myriad sources, a strange and varied list including everything from Martin Scorcese to “The Simpsons.” However, his comedic sensibilities inevitably come back to Woody Allen.

“Woody Allen... is pretty much the premier comedic filmmaker of all time,” he said, “I think that he achieved so much emotion and so much reality to the relationships and so much beauty in these films while still being hilariously funny and making complete films.”

Both men have fairly busy schedules ahead of them. Hill is currently working on “Moneyball,” a film adaptation of the book of the same name, as well as awaiting the release of his film “Cyrus.” Brand, on the other hand, is heading into production for the remake of Dudley Moore comedy, “Arthur.”

“‘Arthur’’s going to be out next year and it’s going to be a fantastic film,” he said. “I’m going to be nude a lot.”