Bigfoot, Yeti, Sasquach, Abominable Snowman, are these one and the same, or different creatures?

I heard about this report on the radio today. The guy being interviewed said they found footprints 15”-17” long and deep enough to indicate a body weight of about 600 pounds. Do you think these creatures exist, and if so, are they all the same creature?
Also: is it possible that we have not discovered all large life here on Earth?