"That's absolutely true. I always joke that we have probably the best jobs in the world because, unlike our husbands who have to react and respond to crisis on a minute-by-minute basis -- they come into office with a wonderful, profound agenda, and then they're faced with the reality," she said, getting a laugh from the audience.
"On the other hand, we get to work on what we're passionate about," she said.
"And I just found it just a very freeing and liberating opportunity."
Asked whether a first lady might be something of a state prisoner, Obama got another laugh when she said: "No, there are prison elements to it. But it's a really nice prison, so ... . "
"But with a chef," said Bush, who was first lady from 2001-09 when her husband, George W. Bush, was president.
Obama said she is constantly asked whether she is "more like Laura Bush, or are you more like Hillary Clinton? And I'm like, is that it? That's all I ... " and then her answer was drowned out by more laughter.
"Exactly the problem," Laura Bush said, "everyone said -- reporters -- are you Hillary Clinton or Barbara Bush? And I always just said, well, I think I'll be Laura Bush; I do Laura Bush pretty well, having grown up as her" -- drawing yet another laugh.