I think there is enough of a difference that it could mean the difference in lets say, how many objects can be in a single space and draw distances. maybe game load times etc. But like you said, there will be little noticed, I mean, they are not going to make one game for 2 consoles and have one that has more going on for one system. At least I do not think so.
We will have to wait until they are both out and have a side by side test on the same games, checking graphic quality, FPS, Load times etc. As we know in the xbox 360 and PS3, there is very little difference at all if any. Hell all I can make out is one has a little lower or higher contrast setting than the other.
But just curious, what if the PS4 was a bit more powerful. Lets say games would load 30% faster. would that make a difference to anyone enough to switch systems?