noun clause 中的 that / wh-words?

He wants to know where you live.

where 是疑問副詞「（住）在哪裡」，引導名詞子句當 know 的受詞。

My opinion is that you are wrong.

that 是連接詞，本身沒有意義，單純引導名詞子句當做主詞補語。