A lot of examples of this occur. Vice City Stories was a different engine from Vice City(LEEDs vs RenderWare). You really couldn't tell as a player. Castlevania and Castlevania III were two different engines, again, hard to notice because that was the intention. Or Mario 64, Mario 64 DS. Two different engines, and funny because Mario 64 DS engine was a ground up development, not a port.
Just because they updated an existing engine to run on new platforms, doesn't really make it a new engine in my book. Just the same engine under a newer set of instructional dependencies. Of course, doing just that much is a ton of work, so I don't want to make it seem as if Visual Concepts just slapped a few lines of code onto it, and called it a day. But seriously, they aren't fooling everyone.
Why is it important? Well, you as the user, are paying for a new game every year. 40-60 bucks. And think this way, hundreds of games are build a year that are build on ground-up engines with far more elements and interfaces. Sometimes as much, if not more licensing fees to use trademarked and restricted content, yet the price is the same per game.
Alright. I'm done ranting about this. I just hope more people get the hint to not fall into the Madden loyalty trap and get milked by 2K. As FT said, FIFA is amazing, and Fifa refreshes the engine far more than any major sports franchise. There is a reason why, and that's because PES is giving it competition. Just like 2K gave Live competition, etc.