Nope. Not the same. That first click puts on the parking lamps (max 125 candela, not anywhere near bright enough to serve effectively as DRLs). The linked article in this thread, and the Freightliner trucks etc., burn the front turn signals as DRLs. They're much brighter than the parking lamps, bright enough to do the job. Also, driving with just parking lamps is illegal in many states. Also, you don't want your taillamps on in daylight. It reduces the on/off contrast of your brake lights, making them less effective. This is the kind of thing I'm talking about when I mention implementation-related disadvantages. I could lecture about it for pages, but it'd put y'all to sleep.
JD340 is absolutely right - one of the BIG disadvantages of headlight-based DRL systems is they lull drivers into thinking their car has automatic headlights...they drive around at night and in bad weather with just their DRLs. Tons of glare, no side- or rear-visibility.