There is a huge difference in about “knowing” something and in “to understand” something.
Its like a two yr old girl/boy knows who is Papa, Mom, Dada and Dadi, because we told her/him so, but they do not understand anything about Papa or Mom and so on. When kid becomes about ten yr old or so they started knowing why you are her/his Papa/Mom/Dada or Dadi. But still he/she do not understand all about this relation until he/she become Papa/Mom and that is the time he/she started understanding what Papa/Mom is all about and later on what Dada/Dadi is all about when they become Dada or Dadi.
Kisi cheej ko Janana, Samajhna aur ooska Gyan hona alag alag stages hain, until unless we do not have that experience we do not have full knowledge about the same.