But girlfriend Vanessa Hudgens, 21, sees a transformation on a bigger scale.
"I look at him, and I see a man," she tells Glamour's August jeans issue of her beau, 22. "He's just grown-up."
When the two first started dating in 2006, Hudgens recalls Efron being "adorable. I mean, he wasn't the guy that he is today. Like, he had a gap in his teeth! He was a whole different person."
Though she doesn't say whether or not it was love at first sight, "Right off the bat, we had a connection, I think everybody could see it," she reveals to the magazine
But this isn't just puppy love. "I guess [we have a mature relationship]," she says. "I think that we inspire each other. [I love] having someone to grow with."
While Efron may be the more adventurous person in the relationship – he went bungee-jumping in Vancouver in July and loves backpacking and hiking – his girlfriend of four years is still a bit hesitant about trying out new things.
"When I was younger, I used to be super, super shy. I still find myself being scared of things," she says, adding that she wants to try kite and paddle surfing one day because it "would give me that extra confidence."
But what Hudgens dreads the most: stepping on a red carpet. "Going to events gives me such anxiety. I get hot flashes! I can't breathe, and I get claustrophobic," she says. "It's a very odd business. I don't know if I'll ever get used to it."