His grandfather's grandfather was his great-great-grandfather. Five generations up from him to his great-great-grandfather (himself → father → grandfather → great-grandfather → great-great-grandfather) were his direct relatives counting up from his five generations, belonging to the same ancestor.
His father's father was called grandfather, and his father's grandfather was called great-great-grandfather, so his father's grandfather was not his grandfather.
" Grandfather " and " grandpa " usually referred to the same person, both of which were the names of the father's father." Old grandpa " could also refer to grandfather, but it was a more spoken, intimate, or respectful term.
His grandfather's grandfather was his great-grandfather. In the traditional order of seniority, starting from oneself, it was father, grandfather, great-grandfather.
In the traditional China family hierarchy, grandfather was the father of father, great-grandfather was the father of grandfather, and great-great-grandfather was the father of great-grandfather. In the common family hierarchy, there was no such standard address as " great-grandfather." If one were to infer according to the logic of family seniority, great-grandfather might be an ancestor who was one generation higher than great-great-grandfather, but this was not the traditional family seniority title.
The grandfathers of the same grandfather belonged to the same generation. In China's kinship system, one's grandfather was the grandfather, and his grandfather's grandfather was the great-great-grandfather. In traditional family relationships, this kind of kinship belonged to the older generation. From the perspective of family reproduction and family lineage construction, they were the ancestors of the family many generations ago.
Grandfather was grandfather, grandfather was father's father, and maternal grandfather was mother's father.
His father's grandfather was called great-great-grandfather, or great-grandfather.
His grandfather's grandfather was called his great-great-grandfather. In the family relationship system, great-grandfather was grandfather's father, and great-great-grandfather was grandfather's grandfather. There might be different names in different regions, but according to the traditional family relationship, the official title was great-great-grandfather.
Your grandfather's grandfather is called Gaozu.
Yes, great-great-grandfather was great-great-grandfather's father, which meant that he was great-grandfather's grandfather.