Spectrum/shape of the spectral efficiency curve. Sure, you can get a vague color temperature match out of LED, but it's HARD to get a curve out of LED that look

Spectrum/shape of the spectral efficiency curve. Sure, you can get a vague color temperature match out of LED, but it's HARD to get a curve out of LED that looks at all like sunlight or like tungsten incandescents. And even the really good ones are noticeably deficient in reds. I can totally believe that if they're attempting to simulate a sunrise there's nothing like massive incandescents.