Does a noun and a pronoun both change form depending on the sentence?

No, not depending on the sentence. The changes in form for nouns and pronouns is based on their use in a sentence.

Nouns change form from singular to plural or they can be common or proper.

Pronouns change form based on singular to plural and case, their function as subject or object.

Noun examples:

There are several churches on this street. The church you're looking for, First Baptist Church, is at the intersection of Main and Fourth Streets.

Pronoun examples:

I live next door to them. They have a red brick house, the one with the black door is theirs.