There is no argument about that.
They are different engines. And the original poster wanted to know the differences - which I'm pretty sure if he went online he could find the exact schematics for each engine and drivetrain and see the differences for himself.
Everyone else wants to justify their purchases which is fine. Some people want more power and if available will buy it.
If possible I would always buy an RS not just an S version of a car for example, but in my case for my van there was no choice as my budget would not cover the £10k premium for 4wd 204.
More power in my opinion is always better and 4wd vs 2wd is not even a contest.
However, if you want more power (which you clearly don't) it's ok! I will remap my van when it's out of warranty just for the increased torque and lower fuel consumption.
I always have remapped every vehicle I've owned.
However I will not be converting to 4wd... it would cost £10000s if it even can be done so I'm stuck with 2wd - but that's fine! I have Snow Chains and Socks and those have always got me out of any situation. It's just not as easy as built in 4motion.
If anyone wants to swap my 150 2wd for 204 4motion with Difflock PM me