1. Middle school is the same.

2. Elementary school is the same.
3. Middle school is not the same as elementary school.
4. Middle school is different from elementary school.
------------------
In each sentence, Is 'same' an adjective or a pronoun?

#3 is the same as #4 in meaning.
If 'same' is the opposite of 'different,' is 'same' an adjective? Or is 'same' a pronoun?

It's an appositive. "She is my teacher." "She is not my teacher." 'teacher" is the appositive, in this case a noun. "same" is an adjective in these sentences. "...is the same...", used as an appositive, as in "The tree was tall."

PAPER

In the given sentences, 'same' is used as an adjective. An adjective is a word that describes or modifies a noun or pronoun. In this case, 'same' is describing the noun or noun phrase that follows it. It is used to indicate that two or more things are identical or have no difference between them.

In sentence #3, 'same' is used to describe the relationship between middle school and elementary school, indicating that they are not identical or have no difference between them.

In sentence #4, 'same' is used to describe the relationship between middle school and elementary school, indicating that they are different or have some variations between them.

In sentence #3, 'same' and 'different' are used to contrast the similarity or difference between two things, while in sentence #4, 'same' and 'different' are used to compare the two things directly.

To determine if 'same' is an adjective or a pronoun, you can consider its function and usage. Here, 'same' is functioning as an adjective, modifying the noun or noun phrase. It is not replacing a noun (which would indicate a pronoun) but rather describing its relationship with something else.