Noah Millman explains how the foreign policy of Trump and Cruz differs from Rubio’s:

I think the right label, for both Cruz and Trump, is “To Hell With Them Hawk,” a coinage invented by John Derbyshire back in 2006. That’s a bit cumbersome as labels go, but we need one, and I think this one will do, because it expresses the degree to which the defining aspect of the rising hawkish dispensation is not really caring what happens as a result of American actions, provided those actions are plainly aimed at killing our opponents.

I think that’s right. The main difference between the Trump/Cruz-type hawkishness and Rubio’s neoconservatism is the former is straightforwardly nationalist in its emphasis on American security first (though they are still defining national security very, very broadly) while the latter is more preoccupied with the U.S. as global “leader” and maintainer of “world order” even if it comes at a significant cost to the U.S. While he can’t shut up about American exceptionalism, Rubio is less of a nationalist, and that comes through in his foreign policy arguments. He likes to cite (and compare himself to) JFK, and with good reason: he buys into the “pay any price, bear any burden” fanaticism that Kennedy endorsed in his Inaugural Address. Rubio belongs to the same Wilsonian tradition that Kennedy did. Trump and Cruz may still favor a fairly activist foreign policy, but they aren’t interested in “paying any price” just so that a previously stable country can be turned into a redoubt for jihadists or so that the U.S. can embark on a decade-long experiment in democratizing another country. If we’re using the (very flawed) conventional labels, Trump and Cruz are Jacksonians to Rubio’s Wilsonian, and most Republicans don’t have much interest in or sympathy with the latter.

It’s true that Trump and Cruz don’t seem to care about what happens as a result of American actions so long as they perceive those actions to be protecting Americans. Hence Cruz’s preference to unleash an indiscriminate bombing campaign on Syria. However, as Cruz’s most recent criticisms of intervention in Libya and meddling in Syria suggest, they are more than happy to acknowledge that U.S. policies can in some cases make the U.S. or at least the surrounding region less safe. Rubio is far too wedded to the vision of “benevolent global hegemony” to admit that U.S. actions can be blamed for anything bad, and so the only error that he thinks the U.S. can make is to “withdraw” or “fail” to act. One can easily imagine that Trump or Cruz would refuse to go to war in the name of “humanitarian” interventionism, and it’s very difficult to imagine that Rubio would do the same. I assume that a Trump or Cruz foreign policy would still be a very meddlesome one, but it would probably meddle in fewer places and for different reasons than Rubio’s.