'nother
determiner informal (also nother) uk/ˈnʌð.ər/ us/ˈnʌð.ɚ/
a whole 'nother story/thing/ballgame/issue, etc. 完全是另一回事
used for referring to a completely different situation, often one that is difficult or that you know little about
I've parachuted and bungee jumped but rock climbing is a whole 'nother thing.
I didn't mind being called an idiot, but when it comes to attacking my family, that's a whole 'nother ballgame.
When you're dealing with children, that's a whole nother issue.
He didn't come home last night, but that’s a whole 'nother story. 他昨晚没有回家，但这完全是另一回事。
That's a topic for a whole nother post.