He's a freshman senator elected with heavy Tea Party support who went on to national prominence by taking the Senate chamber hostage in a filibuster he insisted on waging despite long odds of success. He's an unabashed conservative who seems to relish bucking his Republican Party leaders and now is thinking about running for president in 2016.

Rand Paul? Ted Cruz? Trick question. It's both of them.

Cruz and Paul, two rising Republican stars, have so much in common that even Senate colleagues are at a loss to describe the differences between them.

“I don’t know that there’s an easy answer,” said Sen. Tim Scott, R-S.C., before enumerating their similarities instead. “They’re both fairly assertive, direct, strong men that have a great passion for the legislative process, that have a strong desire to do things that are important for the country.”

But as Cruz roils fellow Republicans with his loud and unyielding opposition to any government funding bill that would also fund Obamacare, an emerging dichotomy between Paul and Cruz has been thrown into high relief.

Cruz’s strategy in the budget debate, marked by a dramatic though largely symbolic 21-hour speech on the Senate floor, has won him admiration among conservatives, in part because he has acted without regard for cautious Republican leaders.

Paul has taken a more nuanced approach.

“Unlike Cruz, Paul is not only playing the outside game, but he seems to understand the importance of working with his Senate colleagues — not blowing them up,” said a Senate Republican aide. “This collegial approach could certainly help Paul in the long run beyond the Senate. Paul seems to value the benefits and importance of not dividing the party, generally.”

While Cruz fights over ideology, Paul leads a rising libertarian faction within the party. Cruz rallies activists outside the Beltway. Paul focuses on policy and earned a reputation in the Senate for working within the body’s traditional framework and with quiet consideration for colleagues. The tack earned him respect even from those who disagree with him, including Sen. Lindsey Graham, R-S.C.

Graham and many other conservatives view Cruz as a bull in a china shop, but they appreciate what's driving him.

“Ted’s new, he came here with a lot of passion, he was the underdog in a primary, he feels really beholden to the people that helped him in the primary, and I understand that,” Graham said.

Cruz readily presents himself as someone less concerned about winning over colleagues than rallying conservative voters and media.

“There are too many politicians, in my opinion, in both parties, who are not listening to the American people,” Cruz told the Washington Examiner.

Over the course of the government funding debate, however, Cruz has emerged as more of an inside operator than he admits — though in the House, not the Senate.

After the Senate approved a measure that funded the government and restored funds for Obamacare, Cruz called some of the House’s most conservative members and urged them to reject the Senate’s bill even though House GOP leaders wanted to put the budget debate behind them. He told the Examiner it was just the latest of ongoing discussions he's had with House members throughout the budget debate.

House Republican leaders were privately furious.

“I have no particular reason to believe that Senator Cruz talking to House members is a unique thing to happen, but it’s usually not very well received,” said Sen. Roy Blunt, R-Mo., a former House leader.

Cruz and Paul's exertions have, for now, pumped up their fundraising, but the longterm impact on their 2016 presidential ambitions remains a matter of speculation.

“Cruz's grandstanding will cost him long-term, smarter Rand Paul silent,” media magnate Rupert Murdoch offered on Twitter this week.

That very grandstanding has won Cruz fresh acclaim from ardent conservatives. Tea Party Express Chairwoman Amy Kremer said she has come to see Cruz as the next big Tea Party hero in the mold of former vice presidential candidate Sarah Palin or former Rep. Allen West.

“What Ted Cruz has accomplished, he has everybody running scared, especially Republicans, and nobody knows what to do with him,” Kremer said.

But Kremer doesn’t yet see enough of a difference between Paul and Cruz to support just one of them.

“Either one of them would be an incredible leader," she said. "They’re both Team America, and that’s what team I’m on and this movement’s on.”