I am trying to figure out the difference between supervised and unsupervised learning.

This may be a stupid question, as I understand it PCA is definitely a form of unsupervised learning that groups, in this case anyway, a selection of texts based on similiarities. My question is, is it considered supervised learning if there is a dictionary assigning certain attributes to certain words or phrases, or does that not matter because it is being mapped on after clustering has taken place. I apologize if I have not been clear but anyhelp would be appreciated