Compared to DVD, a Blu-ray disk provides:

• more than double the horizontal and vertical resolution of the picture (1920x1080 vs 720x480). This difference in picture sharpness and clarity becomes extremely obvious when watching a movie on an HDTV, particularly as the size starts to go above 34"
• better picture contrast and richer color
• high resolution "lossless" audio sound tracks

You asked about a "DVD recorder" - which is a device which can (a) play DVDs as well as (b) record a standard definition video source on to a DVD. Blu-ray recorders (not to be confused with Blu-ray disk burners designed for use with a computer) are only slowly starting to become available.

Umm.. EVERYTHING except recording in standard definition!

There is a substantial leap in picture quality going from DVD to BD, but not as huge as VHS-to-DVD.

Go into any store and watch any computer-animated BD on an HDTV to see the biggest difference.

Mathematically the leap from DVD to Blu-ray is greater than VHS to DVD.

Blu-Ray is amazing! In my opinion, the best one to date is the PS3, its so versatile.

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"Come to the lightside, we have milk..."

Does a Blu-Ray player allow you to record and save broadcast TV footage?  If not, you may want both.