Blu-ray rip same as buying blu-ray disc?

[SonyXBRtv]

This guy is telling me there is hardly any difference between a blu-ray rip and buying a blu-ray disc. Is he right? I dont think he is but I need evidence...if there is any?

Me:

You think downloading "blu-ray" from the Internet is same quality? You are greatly mistaken.

Him:

It's a tough one to answer, it depends on the movie, and encoding settings. I can see the difference. but to be honest, it's pretty small. x264 is a darn good encoder and a good chunk of the viewing audience won't notice a difference between a BD and an mkv rip. and yea... it all depends on the settings, source, etc. for example with an animation movie it's really hard to tell the difference.

Blu-Ray movies are ripped using MKV which is just a container, and x264 is just a way to encode H.264/AVC video. Blu-ray movies are already quite highly compressed from the original source using the H.264/AVC, VC1 or MPEG2 codecs. The MKV versions you might download tend to further compress them to about half that size, sometimes less. Sometimes the Blu-ray may be encoded at a higher bitrate than it actually needs, so you can reduce the bitrate without losing much quality. However, every time you recompress an already-compressed source you're bound to lose some quality. Whether it's noticeable is another matter.

and lastly most of the scene groups that release bluray rips in 1080 and 720 use like 7 pass ripping methods using the best codec settings, so it is very difficult to see the difference.