PHILADELPHIA - Some of the differences are obvious, such as the frantic pace of Eaglespractice that makes it look as if there is a fast-forward button on the players.
Or the ball boys standing at the line of scrimmage wearing shoulder pads attached to what look like 3-foot-high fly swatters, simulating massive defensive linemen with their hands up to make the quarterbacks avoid hitting them with passes.
Or the pre-practice stretches with every player of every size kicking each leg up to his hands, walking while stooping low, forward and backward.
Then there are the individualized shakes players drink, the elimination of junk food from their diets, and the former Navy SEAL who is "sports science coordinator" and pushes players to stratospheric levels of fitness.
Welcome to Chip Kelly's world, a newfangled approach to coaching NFL players. It's perhaps the most intriguing story line heading into the season, and the dominant theme for an Eagles team looking to climb back to respectability after bottoming out in Andy Reid's 14th season.
Can Kelly, who dominated as the Oregon Ducks' offensive mastermind, translate his unconventional style to the NFL, where change is often slow to be accepted? Or will he join Steve Spurrier, Bobby Petrino and Mike Riley as brilliant college coaches who couldn't hack it in the NFL?
The 49-year-old Kelly can't wait to provide the answer.
"It's football at its highest level, and you're going against not only the best players, but the best coaches in the world," he said after Wednesday's's joint practice with the Patriots for Friday night's preseason opener. "That's the challenging part, which is really, really exciting."
Kelly is baffled by all the skepticism about whether his ideas can work.
"I am just confused by it," said Kelly, who went 46-7 at Oregon. "We're a football team. I don't know what 'thing' they keep talking about. We run the same plays everybody else runs. We throw the ball like everybody else throws the ball. I think too much is made of what we do or how we do it."
But let's face it. No one knows if Kelly's pedal-to-the-metal attack, which stresses speed, quickness and running as many plays in quick succession as possible, will start a trend. Or if it's a far-fetched scheme that can't be replicated at the pro level.
Kelly offers assurances that his approach will bear the hallmarks of actual NFL games, not the video-game reputation his offense carries.
"I just think the [fast-paced] offense is a tool in a toolbox," he said. "I would think it's safe to say it's not what we do all the time. It wasn't what we did all the time at Oregon. When you need it, you have to be able to execute it. When we teach it that way, our guys can execute it when we have to."
Kelly's offensive ingenuity actually took root in the NFL before he got here. Bill Belichick has adopted some of Kelly's theories, and the Patriots set a record with 1,191 plays last season.
"I have so much respect for Chip and what he's done," said Belichick, who befriended Kelly a few years ago. "I'm sure Chip will have [the Eagles] in a very competitive situation."
Kelly laughs when it is suggested that Belichick has gleaned so much from him.
"I think there's a little bit more of me getting stuff from him than the other way around," he said. "We both love the game, so we've always talked football.
"I'm originally from New England [Dover, N.H.], so when I'd come back from Oregon, or even when I was [coach] at New Hampshire, he'd let me come to practice. He's got such a great mind for the game. It's always intriguing. You always learn from it. We just had a talk before practice about a couple of things, and he said, 'That's a great point.' So it's really great to be able to talk to him."
Another coach who thinks Kelly has what it takes to succeed in the NFL: Dick Vermeil. He came into a similar situation when he joined the Eagles in 1976 after leaving UCLA. He led the Eagles to their first Super Bowl after the 1980 season and won one with the 1999 Rams.
"People forget how many great college coaches have ended up being outstanding in the NFL," Vermeil said. "Bill Walsh did great in the NFL. Don Coryell was no slouch. There are so many big-name coaches to come out of college. It's almost assumed that if you coach in college you can't succeed at the NFL level."
It doesn't help that Spurrier (12-20) and Petrino (3-10) were colossal failures during brief tenures in Washington and Atlanta, respectively. And Riley, the only one before Kelly to become an NFL head coach with no playing or coaching experience in the league, lasted only three years in San Diego, going 14-34.
Now we'll see if Kelly will join the group that flopped in the NFL. Or whether he'll join Vermeil, Walsh and Jimmy Johnson on the list of college coaches turned Super Bowl champions.