I basically agree with what alaricljs said: there's the feeling of "something inside moving" in the blues, while the browns just feel like you are given a slight warning you have reached the point... but you can continue on? It's much more "together"...
I think the browns are much smoother as well. If I am typing normally, I don't even feel the tactile point consistently, and it's a little nudge compared to the noticeable blues where you feel like you have 'something moving' and then a 'slowing' period where you naturally stop clicking to not bottom out...?
And for lighter... it's only 5g, but you DO notice it, a little.