As Vice President Joe Biden and Republican vice presidential nominee Paul Ryan spar in tonight’s first and only debate, here's what to expect when Biden and Ryan go to head-to-head.

Before we get into the nitty-gritty of what to watch out for, do you know what time the debate is on? Be sure to tune in to the debate starting at 9 p.m. EDT (if you won’t be near a television, here are some live stream options to watch the Biden-Ryan debate online.)

There are sharp contrasts between Biden and Ryan, and those differences are sure to be showcased during tonight’s vice presidential debate.

Strengths:

Biden’s strength, and a huge advantage he has over Ryan, is his foreign policy experience. During his days in the U.S. Senate, Biden was either chairman or ranking member of the Senate Foreign Relations Committee for 10 years. He’s sponsored numerous bills pertaining to foreign policy and was considered as a potential U.S. Secretary of State if Democrats would have taken the White House in 2004.

Conversely, Ryan’s tenure in the House has been marked by his domestic agenda, including his controversial budget plan. As head of the House Budget Committee, Ryan has been an influential member shaping the Republican agenda. He also sits on the powerful House Ways and Means Committee, which plays a vital role in tax policy.

Weaknesses:

Both vice presidential contenders will have to avoid pitfalls if they want to be declared the winner of the debate.

For Biden, the most obvious trap to avoid is delivering another gaffe in what have been countless oratorical missteps since being Vice President. Republicans pounced on Biden when he told a black audience during a campaign stop that Romney’s policies would “put ya’all in chains.” Any gaffe committed during the debate will be magnified due to the matchup being viewed by a national audience.

For Ryan, the Republican Wisconsin governor has to give the impression to voters that he would be a competent president. This is the most important role of a vice presidential nominee, and Ryan’s inexperience (he’s only 42) draws superficial comparisons to 2008 Republican VP nominee Sarah Palin. Look for Ryan to shake off the inexperience questions with answers pertaining to his House career.

Aggressiveness:

How aggressive will the candidates be in attacking each other?

In his 2008 debate with Palin, Biden had to be conscious of not being too aggressive towards Palin and coming across as a bully. But with Ryan, you can expect the gloves to be off.

 “I expect the vice president to come at me like a cannonball,” Ryan told the conservative Weekly Standard. “He’ll be in full attack mode, and I don’t think he’ll let any inconvenient facts get in his way."

Biden said he’ll try and point out the stark differences between the campaigns by highlighting how Romney’s policies will affect the country.

"I just want to make sure that when I say these things that I don't have the congressman say 'No, no, no, I don't have that position,' " Biden told the Associated Press.

Expectations:

In politics, expectations matter even more than debate performance. It’s why Romney, who had low expectations that he surpassed, was seen as the victor of last week’s debate. Obama didn’t meet lofty expectations, hence his being viewed as the loser. If those expectations were flipped, we may have seen pundits declare Obama the winner of the debate.

So what are the expectations for the Biden-Romney debate?

Because of experience, Biden, who has participated in 17 national debates, is expected to be the more polished debater, penchant for gaffes aside. Ryan, as a congressman, has only had to deal with local issues during debates.

For good reason, both camps are trying to lower expectations for their candidate.

As Ryan and Biden were preparing for the debate, the congressman acknowledged Biden’s debate prowess but also said the vice president has a weakness.

“It's a nervous situation because Joe Biden is one of the most experienced debaters we have in modern politics, but the Achilles heel he has is president Obama's record,” Ryan told CBS News.