So, I thought it would be fun to max out my sneak skill tree just because sneaking is fun. Only about 14 points to go till 100

Anyway, I have the Silence perk, and it says "Walking and running does not affect detection." .. I don't think that's right, because I can walk and run and people see me just fine. Does it really mean you don't make any noise when you sneak around? I still hear my footsteps even when I sneak, and my daggers make that same noise when I equip them, so does the game just play the sounds for your footsteps, etc, anyway, but in the game you're actually really quiet?
Also, I have Dark Brotherhood armor and the boots also have what seems to be the same ability. If I have silence, plus those boots, am I even quieter? Is it possible to be quieter, or is there just 1 kind of quietness? or are they both the same and I can just wear any other boots if I have the perk?
Also if silence makes me silent, does that mean I can wear heavy armor, and still not make any noise when I sneak? Or if I had all heavy armor, except I wore the Dark Bros boots with it?