Actually that is not a stupid question at all, and unless u are familar with 4 pedal polini reedvalves your not going to know.
Basically a standard 4 pedal polini intake is actually a large 2 pedal system with 4 windows, it is made from cheap pot metal which is prone to cracking and breaking, and the reeds are riveted on so they cannot be removed or replaced, w/o grinding away the rivets and retapping the hole for screws, then grinding the screws.... well its a bitch ok. And the standard units come with a louse 2 "O" ring style seal that almost always will have an airleak requiring the use of silicone or rtv sealant.
Now this upgraded reed block 1977 has is much higher quality than the standard one. First off its a true 4 pedal system with 4 individually flapping pedals, second it is not made from metal (or at least I can't tell if it is) its made from some kinda of high desity rubberized plastic or carbon material, so its a lot less prone to breaking and or cracking due to heat and vibration, it should also have a better seal than the standard one to help prevent airleaks. Lastly this upgraded version has screws that hold the reeds on so that you can actually replace them when they get old and worn or chipped etc. Or you have the opportunity to install boysen reeds, or different thickness reeds, so its alot more tunable than the standard one.
Basically I would buy this (and have in the past bought it) when your standard 4 pedal block, A. either fails, or B. the reeds get chipped/wear out. Not only do you get a new block but a better one too.
If you got some money to spend and are going 4 pedal polini on a bike you might want to just pick this guy up as well, especially if your going for max power, and max tunability, reeds can make a big difference on ur setup. reeds are to the combustion chamber as the points are to the sparkplug, its very important they are maintained and tuned appropriately.