Blu-ray media

I have a blu-ray movie that I want to backup and need to know what type of DVD media do I need to backup this movie? Is all blu-ray movies have the same amount of video? What would be the best blu-ray blank dvd media used to burn any blu-ray movies?

BD’s come in 25gb and 50gb but thats all I could say since I dont burn blu’s myself because the price for blu blanks and buying a blu movie is about the same price.

Sony and Verbatim are both good BD discs.