MALE VOICES: difference between head voice, open chest and covered chest

I DON'T OWN THESE VIDEOS AND I AM NOT ASSOCIATED WITH TIO. I saved them as an old subscriber and I am sharing them because they are constantly being removed and it looks like they will never be back. I didn't save the controversial content of their short comeback (saying Callas wasn't good or chest voice is bad) because it was very suspicious and completely opposite of what they advocated for over a year, but I will gradually upload all their videos from before their channel went down for the first time that I know were 100% made by them.