America may be adding millionaires at a rapid clip, but currently there are only 400 people who've achieved the ever-elusive billionaire status. 

We couldn't help but ask ourselves –– what does someone do with that much cash?

"If you had a million dollars of investable assets, you're concerned with making the money last," said Tom Orrechio, a principal at Modera Wealth Management in Westwood, N.J.

"If you have a billion, that's not an issue."

Orrechio has been working in wealth management for more than 20 years and served a year as chairman of the National Association of Personal Financial Advisors. His main clients are millionaires and the firm serves about 500 families. But Modera handles more than $1 billion in total assets and Orrechio is familiar with the process many billionaires use to manage their 10-figure sums.

Turns out a few zeroes make a huge difference. Bllionaires require a fleet of financial specialists to make sure their finances are up to snuff. 

They don't just hire financial planners. They hire financial officers.

A millionaire might start by hiring a wealth management firm to handle their investments and sticky issues like estate planning and taxes, but billionaires need help deciding how they'll pass on their fortune to their children, how to skirt around taxes, shelter their assets from creditors, orchestrate their charitable contributions, and help diversify their property and other investments.

Hiring a financial management officer is top priority. A billionaire often hires several people to work directly for them in a "home office," doing everything from paying monthly bills to handling travel expenses, Orrechio said. It's like a mini-corporation and one-stop concierge service all in one. 

"If you're a billionaire, you might be making large gifts. You have more sophisticated estate/tax planning, [and might manage] multiple legal entities," he added. "You have different individuals to handle those entities."

People who fall in the middle of the millionaire and billionaire range often hire a financial team to cover several families in their income bracket.

"The Rockefellers are a good example," Orecchio said. "What a lot of these wealthy families decide to do, they have the scale and infrastructure costs covered, so they can open up to multi-family office."