Sarkozy, too, acknowledged differences but played them down.
"Do we agree on everything? No," he said, an apparent reference to the divisive Iraq war.
"Because maybe even within a family there are disagreements, but we are still a family. And we may be friends and not agree on everything, but we are friends."
Bush called Sarkozy a friend who could be counted on to speak frankly.
Sarkozy, visiting Bush for the first time as France's president, arrived with plenty of his own praise.
He focused on more than two centuries of united history between the countries, thanking the US for sacrificing lives to help defend France in time of war.
Bush, Sarkozy, and Bush's father, the former president George Bush, held a private meeting for about 50 minutes before lunch.
The US president said they were to have a "heart-to-heart talk" about key issues, including Iran.
The invite to the Bush family estate in Maine is unusual. Bush usually invites foreign allies to his ranch in Crawford, Texas, to show a special relationship.
The last head of state to visit the ranch was Alvaro Uribe, the Colombian president, in August 2005.
Only one other foreign leader has been invited by Bush to his family's Maine seaside compound - Vladimir Putin, the Russian president, was invited in July to try to soothe escalating tensions over US missile defense plans in Europe.
Sarkozy arrived at the Bush Walker's Point estate from nearby New Hampshire, where he is on his first holiday since taking office in May.
The American holiday, which has drawn criticism in France, was briefly interrupted when Sarkozy flew home to attend the funeral of Cardinal Jean-Marie Lustiger on Friday.