Probably worse quality than the retail BD, highly compressed. Not sure i have never used VUDU.
I mean you take the same master and compress it further how is it going to look better?
Why would you compress it further? BD is 1080p. Digital HD simply means 1080p (or 720p) sent digitally (no media). There's no need to recompress.
Because no streaming file even in 2015 is going to be 50 gigs of data. As far as i know, maybe i have old information.