And even though James recently called for basketball greats to stop being judged against one another, he says he's OK with the comparison being made between him and Simmons.
"I don't mind it," James said Friday before the Cavs' 114-108 overtime loss to the New Orleans Pelicans. "Someone's going to be compared to someone all the time, and I don't mind him being compared to me. People not only recognizing what he does on the floor, but he's a great kid, too. He has a great family, great support system, and that's why he's able to do what he [does] on the floor."
Simmons attended Friday night's matchup, taking a seat in the section behind Cleveland's bench in the third quarter.
"He's one of the best players in the world that's played the game," Simmons said in an interview with ESPN. "I just try to take little parts of his game and put it into mine. His size is one of the things that I look at. I'm 6-10, and he's right at 6-8 or 6-9, and I just try and fit what he does into my game."
Simmons, playing in nearby Baton Rouge, Louisiana, has taken the NCAA by storm, averaging 19.9 points, 14.9 rebounds, 6.0 assists, 2.4 steals and 1.6 blocks through the Tigers' first seven games.
James said his relationship with Simmons, a native of Australia, goes back long before college.
"I've watched him a lot, but I've watched him way before he showed up at Baton Rouge," James said. "I've been on him for probably three or four years now, and he's an unbelievable talent."
The pair also spent time this past summer at the Nike Basketball Academy in Santa Monica, California, where James was an instructor and Simmons was a counselor. The two also regularly speak on the phone.
Simmons likened James to a big brother.
"He gives me a lot of advice if I ever need it," he told ESPN. "He looks out for me, and he's one of those people you have to have as a mentor because he's one of the best players in the world."
While Simmons was already considered a potential No. 1 pick in the 2016 NBA draft before LSU's season even started, some of his performances have been eye-popping, including 21 points and 20 rebounds against Marquette and 43 points, 17 rebounds, seven assists, five steals and three blocks against North Florida.
Yet James said nothing Simmons is doing has caught him off guard.
"Nah, I'm not surprised," James said. "He's a talented guy. The coach [Johnny Jones] at the university allows him to showcase his talent, and that's what he's capable of doing."
Information from ESPN's Israel Gutierrez was used in this report.