What is the difference of a meaning of the following two sentences;
1) It is a group of words used as a noun.
2) It is a group of words that is used as a noun.
The #1 sentence has a "used" as an adjective. The #2 sentence has a "that" as a relative pronoun? But, I don't know how this difference would affect the message from these sentences. Please, I would appreciate an advice.