A lot of what idleprocess posted above, but basically anything that pulls attention away from the task at hand (driving), while not serving any useful purpose.
I don't see different-looking DRL's as being a distraction, because the DRL's are on other vehicles, and being aware of DRL's means you're aware of the other vehicles, which is part of the task of driving.
Whether the DRL is a white LED, amber turn signal DRL, low beams, or low intensity high beams, ultimately the result is the same - I notice the vehicle more readily.
This is especially apparent in adverse conditions like an overcast sky, with a dark or grey colored vehicle. It makes judging the presence, position, and approach speed of the vehicle easier, which is important if I'm waiting to make a left turn, or if the vehicle starts veering into my lane.