Mechanically, spec/tech wise - zero difference. Aesthetically, I believe the 650s match my hair color better. The 650s cost about $130 more, come in a different box and have a slightly longer cable. I found the Drop cable to be too short for me at just 6ft long. But, you can buy the "stock" 10ft cable which is about $20 retail, easily around the web. Even with that, you're still saving $110 on a great listening experience.