In addition, 47 percent of millennials, compared with 24 percent of boomers, say family assistance with finances and housing will be an important part of their financial security in retirement.

But 40 percent of boomers aren’t planning on leaving an inheritance at all—with 57 percent of boomers not believing they’ll have anything left to leave anyone, and another 35 percent planing to make sure they don’t by spending whatever they have on themselves. Oh, and 44 percent don’t even have a will.

That’s not all the surprising news about millennials, though. They fully expect to retire young, planning on quitting work by the time they’re 59. That’s an average of six years earlier than boomers, who are shooting for retirement at age 65.

But there’s a flaw in millennials’ plans, since they’re only saving at a rate based on their expectation to live for 25 years in retirement—making them 84 years old when they run out of money (whoever's money it turns out to be).

They’re not planning based on data from the Social Security Administration that one out of every four 65-year-olds today will live past age 90, and one out of 10 will live past age 95.

They’re also not planning on the impact of inflation on what money they are saving.

Just 17 percent of millennials say they’ve factored inflation into their retirement savings planning, even though a 3 percent annual inflation rate could turn today’s $100 purchase into one that costs a retired millennial $181 instead—that’s going to eat up savings a lot more quickly than they anticipate.

The survey also finds that the cost of long-term care and out-of-pocket health care expenses are considered the biggest threats to financial security in retirement by both boomers and millennials.

Houses play a big role in retirement planning, with nearly half of Americans—49 percent—including 60 percent of millennials and 43 percent of boomers planning on cash from the sale of their homes and/or businesses to pay their expenses in retirement.

In addition, at least a third of married couples, 33 percent of millennials and 35 percent of boomers, say their spouse’s retirement savings will be very important.

One source of help they’re not looking to is the federal government, with just 37 percent expecting that Social Security will be a very important source of retirement income. That includes 47 percent of boomers and 35 percent of millennials—with 41 percent of millennials not even expecting that Social Security benefits will be available by the time they retire.