According to the load screen screen detection is controlled by the weight of your armor, the line of sight, the speed you are moving, and the lighting. Of course, you can have Dawnbreaker glowing white hot an inch from a Vampire and he won't see you, so I think they mean lighting spells and ambiant lighting. In general, the above would be seperated into a sound multiplier and a sight multiplier. I have no proof of this, but I beleive this is still the case with blind enemies such as Falmer. Their ability to "smell" you is still LOS based. The sounds multiplier can be affected by all the relevant perks. If you wear advanced DB boots and have the running perk, you will be silent even if you are wearing full Daedric. However, ONLY the sneak skill (and the top sneak perk) affect how well you can remain hidden from sight. And, even if you are silent, if your companion tips off an enemy, they are LOOKING for you, not listening for you. So, even if you are a master sneak, if you are not in shadow, they will find you.