There are 3 kinds of blu-ray copies: BD ISO, BD remux, and BD rips
a
BD ISO is an
exact copy of the blu-ray disc itself. It's virtually the same as the original, and contains everything (including menus, special features, etc.) HDD space consumed would be up to 50GB per disc.
a
BD remux is an
exact copy of the movie(main feature) found on the blu-ray disc. Video quality will be exactly the same as found on the original, audio track included will typically be lossless (Dolby TrueHD or DTS-HD Master.) Compared to BD ISO you only get the movie, not the menus and everything else. HDD space consumed would be typically 20-50GB per movie.
a
BD rip is a
re-encoded copy of the movie(main feature) found on the blu-ray disc. Video bit rates are encoded at lower rates, audio tracks included are typically lossy (Dolby Digital or DTS Core.) HDD space consumed per movie would typically be 4-6GB for 720p and 8-12GB for 1080p.
Whether or not there is perceptible difference between a 720p BD rip vs the original quality as found on BD/BD ISO/BD remux would depend on a lot of factors as mentioned above.
Personally i enjoy both the original BDs and downloaded 720p movies equally well, too busy on enjoying the movie instead of nitpicking on the subtle differences in quality. things would be different though if for example i have faster internet connection/larger TV, i would opt for BD remux more.
another question may mga FULL HD Player na USB ang connection sa TV at yung iba naman HDMI connection nya.ano mas maganda sa Dalawa???
All media players connect to the TV via HDMI. Some TVs, particularly Samsung and LG if I'm not mistaken, have media players built-in, hence you can play movies via USB flash drive/external HDD connected straight to the TV.