Another reason why the contract isn't comparable: Couturier was a 23 year old in the middle of his second contract that would have brought him to RFA status.
Danault is a soon-to-be 28 year old, pending UFA.
By the way, Brandon Sutter got a similar deal to Couturier and while the deal wasn't good, it's gotten better due to the cap going higher. Kinda similar to Mathieu Perreault. Another comparable: Jordan Staal, although Carolina foolishly paid him thinking he'd be a #2 center.