Manchester United manager Van Gaal is entering his first season in England's top flight after being unveiled last month and he has hit the ground running, winning all five of the club's pre-season fixtures in the United States.
United capped a successful tour with a come-from-behind 3-1 victory over Rodgers' Liverpool side in the International Champions Cup final on Monday.
However, with the real business set to get underway on August 16, Rodgers has told Van Gaal he will face a tough task winning the Premier League title first up, despite enjoying profound success with Barcelona and Bayern Munich - winning silverware in his debut campaign at both clubs.
"I think what he'll find is the competition in this league will be different from any other league that he's worked in," said Rodgers.
"In a lot of the other leagues there are one or two teams and those are the teams that are expected to win.
"This is a league where the top team plays the bottom team and on any given day you can lose. You don't get that a lot in the other leagues. I think the competition will probably take him by surprise and that's from foreign managers I have spoken to over the years.
"I've worked closely with foreign players who have come in and that real physical competitive nature will be different from anywhere else he's worked before."
Rodgers, who guided Liverpool to within two points of their first league title since 1990, also took aim at United for their handling of former boss David Moyes.
Moyes succeeded Alex Ferguson at the start of the 2013-14 season, signing a six-year deal, but he was relieved of his duties in May as United finished seventh in the Premier League.
"I think there were a lot of things at Manchester United that were not seen by many," the 41-year-old said.
"He had to go in and where I felt for him is that he thought he was getting time. All of a sudden when it's not as hunky-dory as people think it is, you don't get that opportunity.
"He signed a long-term deal and thought he had that longevity to do his work."
United kick off their Premier League season at home to Swansea City on August 16, while Liverpool entertain Southampton at Anfield the following day.
