I did a search for this information and if I missed it please don't flame, just message with a link to the information.

I understand Blueray has high quality but beyond this I'm uncertain to the quality of formats 720p, 1080p DVD, DVDRIP, HDRIP, BDRIP. I thought HDRIP was the same as Blu-Ray. As I see they are both versions available I know this to be not true. Yet sometimes file sized throw me. I'd expect the better quality to be larger but his doesnt always seem to be the case either.

For example I'm looking at "Prometheus" I see a DVDRIP that is 1.37 GB then I see one that that is 716.08 MB

A 1080p version is 9.33 GB! I'm confused.

Thanks

Well, sometimes some people (damn'em) try to dump themselves then people ; create a good copy based on a bad one, it's like Riping a Divx file to Avi, then expecting an Audio/Video improvement (especialy with old release Videos), so don't always judge files based on their size, & so sometimes in same cases an mp4 Rip file could be much better than a file with an MPEG or Mkv extention...
so to find the quality that may suit you, i suggest you rely on users Comments, A/V Rates, Uploaders reputation,... then your "Downloader instinct" x)
Thank you.

What you need to look at is the resolution, bitrate and framerate . Dont be decieved by BlurayRip or HDrip as sometimes the quality is scrapped to make it into a smaller file. The rip only means the source they used for their video, it would most likely be altered though so check the following instead for a more accurate description of the video specificatons.
The resolution is the size of the video in relation to length and width, generally the larger the resolution the better the quality is going to be.
The bitrate tells you how much data is being projected in a space of time and again the larger the amount the more likely it is better quality.
The framerate tells you how many frames are shown in the space of a second. Basically, the more frames the smoother the movie will look. Like a normal gif picture has a very low framerate whereas at a cinema there is a high framerate.
Good luck on downloading your movies.
Inconspicuous OUT!

Just too give you a bit of an idea on the different sizes last night i converted 2 series of boardwalk empire which in their original mp4 format had a file size of 4.85 Gig overall and after converting to avi the total file size was 12 gig, almost 3 times more, with barely any difference in quality

A lot of torrents on KAT supply you with that sort of information if you scroll down on the torrents 'main' tab

some uploaders put in description of the torrent information about the movie,what codec,bitrate..etc
but you can't go wrong if you download with extensions like DVDRip XviD-ETRG,or BHRG,absurdity,maxspeed,PTpOWeR,DEPRiVED and so on ,and so on..I always download movies 700mb size,in avi format,and no complains here...but everyone has their favorites..

Question: what size (GB) are you looking for?
a rough estimate.. may it be 700mb a 1.3gb or larger..
this way we can talk about it a bit better.
have you come across any uploaders you like thus far with movies..

I have no size requirement,(probably not helpful) but I mainly look for a clean image, sharper is always better, with a minimum of fuzziness. "Think like a man BDRip XviD-cocain" unknown torrentwas excellent 1.37GB
Mission Impossible Ghost Protocol 2011unknown torrent was not. Size is probably like trying to decide on quality by quantity

Usually a dvdrip is the dvd version without all the menus, subtitles etc. It would generally be the same quality as the dvd though it might be less if it's been converted too.
It might sound a bit hit and miss but this often works for me - if the dvdrip filesize is what you'd expect, eg somewhere over a gig for the dvdrip, the quality will usually be ok. 700mb ish rips will likely be a bit poorer in quality.
hth
Ragle