What is the physical difference between Blu-Ray and HD-DVD?

Question

What is the actual difference between the disks themselves? Don't they work the same way?

Answer 1

Both use a Blue Laser; however Blu-Ray uses a smaller pitch, so it can hold more data than HD DVD.
On the other hand, you can make HD DVD discs using the same equipment as standard DVDs, so the discs are cheaper to make.

http://en.wikipedia.org/wiki/Blu-ray_Disc