But on the international stage the pair are very much partners in crime, having racked up more than 200 Ireland caps between them so far.
That number is not expected to get much bigger with centre O'Driscoll set to retire from international rugby, but O'Connell is adamant the Leinster legend's impact will continue to be felt.
"He's spread confidence across the whole set-up. You see what guys have become under him," said O'Connell.
"They've realised this is how you need to play the game, you need to be the complete player.
"There's a lot of people who have come through now almost in the mould of Brian, in the way he's carried himself.
"When Brian finishes, that confidence will remain in the Irish set-up because I think a few players have moulded themselves on him a little bit and realised this is what you need to be to be the all-round rugby player.
"What he does on the pitch is just incredible, very often your best attacker isn't necessarily your best defender, but Brian is that, he's a fantastic attacking player but he's an incredible defender, an incredible poacher.
"He's brilliant at the ruck, has a great work ethic, and he's a very unselfish player as well.
"He's actually a very understated and quiet guy behind it all as well."