From classics like Jaws, Godzilla and Creature From the Black Lagoon to modern hits like Pacific Rim, Colossal and The Cabin in the Woods, there is no limit to the what the monster movie genre can create. Moviegoers will never tire of seeing a giant creature wreak havoc on human civilization. But when a monster lays waste to entire cities in a single film, does that mean that flick is also a disaster movie? How deep in the sand are the lines drawn between the two popular genres?

Nerdist figured the best person to ask was someone who has essentially created his own genre of action movies: Dwayne “The Rock” Johnson. The former wrestler-turned-movie star has been in his fair share of monster and disaster movies over the years of his storied career, and he’s about to debut another next month with Rampage. But since Rampage features not one, not two, but three giant monsters destroying a city, does that make it a monster movie or a disaster movie? We traveled all the way to the Atlanta-based set of Rampage last summer to have Johnson explain the difference.

“Well, let me take a stab at this,” Johnson says, still sporting his fake black eye and bloody knuckles from filming earlier that day. “From my experience, the difference between a disaster movie and a monster movie is [in] one you’re dealing with mother nature—very unpredictable—the other you’re dealing with mutated monsters, which are unpredictable, but at the same time, one was a best friend of mine, someone who I treated like my brother or my kid.”

Johnson is referring to his Rampage co-star George, the CGI/mo-cap intelligent silverback gorilla that accidentally gets exposed to a rogue genetic experiment gone awry, mutating the gentle ape into a raging creature of enormous size. Johnson plays primatologist Davis Okoye, who, untrusting of humans, calls George his best friend. That bond between Okoye and George is the heart and soul of the otherwise full-throttle monster movie, and that’s why Johnson signed on for Rampage in the first place.

“I’m an animal lover,” he says. “I have a lot of dogs and horses up in Virginia and I raise fish, so there was this great relationship with an animal in my life that I could apply to it. And I have a little Frenchie named Hobbs, named after the character from Fast and Furious. And amidst the calamity, amidst the science going wrong in the wrong hands, it still comes down to this core relationship, and that’s one of the reasons that really attracted me to begin with to the movie and to the script, because the element and the anchor of the relationship between man and his best friend, and his best friend happens to be an albino gorilla, that sealed the deal for me.”

Johnson then thinks of another difference between monster movies and disaster movies: how it forces the characters to deal with impending doom.

“What I’m finding as we move along and we’re shooting these scenes is that, unlike with San Andreas, we had time between earthquakes,” Johnson adds. “We have a sense that something was coming, that something else was coming, the big one was going to happen. We had a little bit of time. In this, with three gigantic monsters—especially at their height of the serum taking effect—there’s no time and everything happens very quickly, and everything’s happening from different angles.”

Along with George, two other animals are exposed to the gene-altering substance, making the problem a lot worse. “Not only are you dealing with the destruction and the collapsing of buildings in all of Chicago, but then you’re dealing with alpha animals who are trying to do everything they can to kill everything around them,” Johnson says. “And then the fighting for territory, and then trying to get to the beacon; there’s a whole bunch of things happening.”

No stranger to action-heavy roles, it’s downright shocking to hear Johnson call Rampage “easily the most physically demanding role” he has ever done. But he’s serious.

“I didn’t really anticipate it because I knew it was going to be physically demanding because you read the script and you know that things start to happen at a catastrophic level,” he says. “Things are going down all around you and you’re flying a helicopter, plus, I was familiar with [director] Brad [Peyton]. But it wasn’t until I got to the set that you start to realize that it is constant. Unlike San Andreas where a little tremor would happen, a little bit of rumbling, we’d have a little bit of time, this is just a constant onslaught.”

While Johnson does promise that Rampage still has that classic Rock humor peppered in throughout, the action is going to be never-ending, and he hasn’t experienced filming like that ever before.

“From a physicality standpoint, the Fast and Furious movies can be very physical because there’s always a fight,” he adds. “But in this case, there’s a lot of almost being eaten and there’s a lot of running for your life. There’s a particular scene, there’s a big C-17 and George is growing on it, he’s growing rapidly, he’s getting very angry. Jeffrey Dean Morgan is on it, and it’s a terrifying scene that just continues and continues, because the plane is nosediving, and we’re trying to get off it … This is 12 hours every day, and finally Naomie [Harris] is like, ‘F-k, man, this is tough.'”

For director Peyton, discovering new situations and experiences he can put Johnson through is thrilling. “It’s demanding stuff, it’s true,” Peyton says. “I ask him all the time, ‘Have you ever done this before?’ And he’s like, ‘No man I’ve never done this.’ I just assumed he’s done some of the stuff we’re doing, because to me Dwayne’s done everything, including become president.”

Peyton laughs before adding, “But it’s just literally the positions and predicaments his character is in in this movie are so wide ranging and there’s no way to not put him in it. There’s no way I can do the movie and not have him in harnesses and rigs and whipping around. Also he signed off on that script so … he knows what’s he getting into!”

But don’t take Johnson and Peyton’s comments as anything less than enthusiasm for Rampage. Because if Johnson has his way, he’ll be doing these kinds of monster and disaster movies for a long, long time.

“It’s awesome, man. I still feel like I’m a big kid at heart,” he says. “I certainly act like it at times, and at the end of the day, we’re on this treadmill of life and we all try to do good and do our job and hopefully put in good work and learn from our mistakes. At the end of the day, I feel like we’ve got the best job in the world: we love what we do, we’re here in Hollywood, we’re on this big soundstage, and it’s total destruction, and I’m looking up at this giant albino gorilla who’s my best friend [saying], ‘Ready to kick some ass?’ It’s the best. I never take it for granted.”

Rampage hits theaters April 13.

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Images: Warner Bros. Pictures