Subject pronoun vs object pronoun

What is the main difference between adjective clause with subject pronoun and object pronoun?

Solution 1:

The OP didn't give any information, so I will answer one question that might occur to someone:

What is the main difference between a restrictive relative clause with a subject relative pronoun and a restrictive relative clause with an object relative pronoun?

For example,

That's the man who/that saw her. (the man saw her: subject)

That's the man (who/that) she saw. (she saw the man: object)

Well, the main difference is that when the relative pronoun is the object, you can delete the relative pronoun (that's what the parentheses around them means), because the sentence already has a subject, and you don't need to go to the trouble of putting the pronoun up front to mark it as a relative clause.

That's the man she saw

That's grammatical because two noun phrases in a row like the man she is a mark of a relative clause and causes our parser to push down one level and start parsing a subordinate clause. If all you hear is

I like the man she ...

you're gonna understand that the next thing is a verb and she is its subject, so you can afford to leave out which or that here, and still be understood and colloquial.

However, that's not the case with relative pronouns that are subjects. Relative clauses are tensed, and every English tensed clause has to have a subject (or, in an emergency, something resembling a subject, like there or it). If you deleted the relative pronoun in the first example, you'd get an ungrammatical sentence