THD In Light Bulbs

I have replaced a 40w incandescent light bulb with a 12w LED light bulb. The new LED is way brighter. In fact, the box says that it's a 75w equivalent. The box also shows something interesting:

Power Factor >.90  
THD: <35%

I've read that LEDs are essentially diodes. How does this affect noise in the mains? Do LEDs inject more, less, or the same amount of THD into the mains as incandescent/fluorescent lights?