Both are referring to a group of words. However, there are some distinct differences between phrase and clause.
Phrase is a group of words that is:
My best friendWith the blue shirtFor 20-daysClause is a group of words that:
Examples
The falcon soared. (independent)While my guitar gently weep (dependent)As I was scared (dependent)It's a sentence on its own.
I ate the pineapple.The bear roared.That's not our rabbit.It can't be a sentence on its own. Usually, this clause starts with subordinating conjunctions.
Because it was delicious,Although it was dark,While the salmon flocked,Dependent clause starts with a relative pronouns (who, while, which, whose, where)
It's delightful to see that guy that sells the new Willamete cold brew coffee ice-scream.That woman, who always wore a red hat, has the strength of a lion.That one person, who can breach the pillar to its top, be crowned as leader.That candy, which has the red and green stripe, is great!