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DANVILLE, Ky. - Tonight's one and only vice presidential debate will look and feel a little different than last week's first presidential debate.

Like the presidential debates, tonight's debate will last 90 minutes and will not have any commercial breaks. ABC News' Martha Raddatz will be the only moderator, and she alone has developed and will ask the questions - without consultation with either campaign.

Unlike last week, Vice President Joe Biden and Rep. Paul Ryan will be seated, next to each other and at the same table as Raddatz. The look will be similar to the vice presidential debates of 2000 and 2004, though not 2008, when Biden and Gov. Sarah Palin stood behind podiums.

Another difference will be format. Tonight's debate will be roughly evenly split between foreign and domestic topics. Last week's debate was domestic only; there will be a with a town-hall format and a foreign-policy debate to follow over the next two weeks.

And while Jim Lehrer moderated a debate broken into six 15-minute segments, Raddatz's debate will be broken into nine 10-minute segments.

The Romney-Ryan campaign has asked, via the Commission on Presidential Debates, that Rep. Ryan be referred to as "Mr. Ryan" throughout the debate.

At the beginning of each segment, Raddatz will ask the same question to both Biden and Ryan. Each will have two minutes to respond, uninterrupted, with lights giving time signals to both men.

Raddatz will then use the balance of the time in each segment to facilitate a discussion between Biden and Ryan. There will be no opening statements, though both will be given on minute and 30 seconds for closing statements.

As determined in a coin flip, Biden will answer the first question first, and Ryan will answer the second question first, with the order to follow in that pattern thereafter. Biden will deliver the first closing statement, and Ryan will get the final word.

All of the rules have been promulgated by the Commission on Presidential Debates, which set the rules and formats for all four of this year's presidential and vice presidential debates. The commission chose Raddatz as the moderator but the moderator does not have a role in establishing the format groundrules.