What a clause is & What a phrase is
A clause is a group of words that includes a subject and a verb.
Now see this sentence
Ram is a good boy but Mohan is a bad boy.
In the sentence above; it can be divided into two parts namely RAM IS A GOOD BOY; and MOHAN IS A BAD BOY. The first group of word has the verb BE (is) and the subject RAM; the second group of words has the verb BE (is) and the subject MOHAN. Therefore we can say both of these groups of words are clauses as each of them has a subject and a verb.
Some more examples of clauses:
a) Ritu ate an apple after she had finished watching the news.
[If you see, the group of words ‘RITU ATE AN APPLE’ has subject (RITU) and verb (EAT); and the group of words ‘SHE HAD FINISHED WATCHING THE NEWS’ also has subject (SHE) and verb (FINISH); therefore you can say that both of them are examples of clauses.]
b) Even though his mother was a driving instructor, my cousin failed his driving test six times.
[Here the group of words ‘HIS MOTHER WAS A DRIVING INSTRUCTER’ has subject (HIS MOTHER) and verb (BE); and the group of words ‘MY COUSIN FAILED HIS DRIVING TEST SIX TIMES’ also has subject (MY COUSIN) and verb (FAIL); therefore both of them are clauses.]
A phrase is a group of words that stands together as a single unit but does not have a subject and a verb together. A phrase does not contain a subject and a verb and hence cannot convey a complete sense. Now see this sentence
My mother took me to see a film.
[In the above sentence the group of word MY MOTHER like a clause does not have a subject and a verb, therefore cannot convey a complete sense, but it is making a sense certainly. So, it’s an example of a phrase.]
Some other examples of phrases
in the sky, on the table, your books. the school of my village, etc.
But the following groups of words cannot be said as phrases as they all are meaningless:
books are, took me, see a, etc.