Both clause and phrase are a part of a sentence but are different from each other, and this article will explain the phrase vs clause in detail.
-- A group of two or more words in a sentence related to each other or acting as a single unit but does not have a subject or a predicate. Each word of a phrase has a meaning but collectively it does not form complete sense like a sentence. i.e. it does not give a complete meaning when standalone. ex : Fish Swims in the water. / Over the horizon.

-- These are also a group of words in a sentence that have a subject and a predicate (or verb). Clause gives complete meaning and can even be a complete sentence when standalone. ex : Fish Swims in the water. / He smiled.