"Ted has shown a propensity throughout his career in the U.S. Senate to take one position in front of one audience and then change his position in front of another," Rubio said on NBC's "Meet the Press."
The Florida senator also accused his colleague of reversing his public position on immigration reform, saying Cruz backed a plan to legalize undocumented immigrants "in front of one audience, but then he portrays this sort of notion that he's the harshest and hardest when it comes to that issue."
"His record used to be something very different than what he makes it sound like," said Rubio, who sustained significant political damage with conservatives for his role in helping to craft the so-called 'Gang of eight' bipartisan immigration reform package.
That deal, which languished then died in the GOP-controlled House, has since been disavowed by Rubio, who now favors a more piecemeal approach.
Rubio also defended his support for crop insurance in Iowa, home to the first GOP caucuses, and subsidies to the sugar industry, which is mostly based in Florida.
"We are competing against other countries that don't have our regulations, don't have our labor laws, and subsidize their own industries," he said. "And what will happen is if we can't compete, our farming capability goes away."
Cruz has faced tough questions on trail in Iowa for his opposition to a federal program mandating that 10% of gasoline be comprised of renewable fuel, often ethanol that comes from corn.
Rubio also jabbed the Texas senator for his recent string of attacks on so-called "New York values." Cruz last week explained his terminology, describing New Yorkers as "socially liberal, pro-gay marriage, pro-abortion, focused on money and the media."
Those comments, which critics in and out of the GOP contest have criticized, with some suggesting they amount to a dog whistle aimed at anti-Semitic voters or homophobic elements in the party, represent a deeper dishonest, Rubio claimed.
"I think the bigger problem is Ted has raised a lot of money out of New York. He didn't say that when he was there raising money," Rubio said. "He said that in one state and then said something different in another."
Cruz's wife Heidi is a managing partner at Wall Street giant Goldman Sachs' Houston office. During his run for the senate in 2012, Cruz sought and accepted, and his since repaid, a loan from the megabank. But he did not report the transaction
on his FEC filings at the time, leading rivals to charge Cruz misled voters.