What is the difference between a blue ray and a DVD ?

Blu-Ray presents the movie in a higher definition, but if the transfer of older movies isn't done well or you don't have the appropriate TV set up Blu-Ray can look really bad.

I prefer DVDs honestly.

Blu-ray has more space on the disc which allows for a high definition movie to be stored on them!

Blu-Ray is pretty much a DVD that plays movies in HD. That's all you get, a "prettier" picture. Although some argue that DVDs still have a crisper picture than Blu-Ray which still deals with some choppy images during scenes where the camera pans.

A bluray disk is made such as to store many times the data storage capacity of a dvd. A DVD comes in two formats:single layer and double layer . A single layer dvd supports data upto 4.7 gb and capacity of double layered dvd is above 8 gb, similarly single layered bluray disks support data upto 25 gb and double layed bluray disks support data upto 50 gb.