Difference between DVD-R and DVD-RW

I am recording a video of skateboarding using a Digital Versatile Disk-Recordable (DVD-R), however, for some explanation can be refined on the computer. The disk is not acceptable instead I should use DVD-RW for camcorder or Digital Versatile Disc-Rewriteable (DVD-RW) disc to the computer? What is the difference between the two and why I can’t use DVD-R?
