The idea that computers can recognize human voices surprises many people.
The idea that computers can recognize people's voices surprises many people. (appositive clause, which does not act as any component in the clause)
The idea he put forward surprised many people. His idea surprised many people. (attributive clause, that is, the object of gave in the clause)
2. Different leading words
What, how, if, whatever, and so on. Can guide noun clauses, but can't guide attribute clauses.
3. The appositive clause is collocated with the previous noun, which means the content of the previous noun; Modify the attributive clause and the preceding noun, that is, limit the scope of the preceding noun or supplement some situations.
The news that I passed the math exam is true.
The news that I passed the math exam is true. (appositive clauses, that is, clauses express the meaning of the previous nouns)
The news that he just detained me is true. The news he just told me is true. The attributive clause modifies the previous noun, that is, the news "he told me", not other news.
4. The antecedent of the attributive clause is a noun or pronoun; The antecedents of appositive clauses can only be nouns, and they are limited to a few nouns such as ideas, facts, hopes, news, doubts, truth, information, hints, questions, beliefs and conclusions.
Moreover, the antecedents of attributive clauses guided by when, where and why must be nouns indicating time, place and reason respectively, while the antecedents of appositive clauses guided by them are definitely not nouns indicating time, place and reason.
I don't know when they will come. ?
I don't know when they will come. (appositive clause)
I will never forget the day when I lived there. ?
I will never forget the day when I lived there. (attributive clause)