Playing 1080 movies with usb cable?

Playing 1080 movies with usb cable?
Do USB cables downgrade the quality of a 1080p dvd movie from a portable hard drive to a HD 1080p HD TV? The movies are about 1.4 Gb 1080p in mkv and numerous other files… But the question is, should i actually be using a HDMI cable for this to get the real 1080 qualityConfused

Btw, Yes the movies work on my tv with usb cables, i have no problem playing them. I just want to know if USB cables automatically reduces the 1080 quality to 720 quality