"Clarity" is just a slightly formal word for "clearness." I can't think of any difference in meaning.
"The new sound bar we bought for our TV has a 'dialog' setting. It improves the clarity of spoken dialog." It makes dialog sound clearer.
"Section 5 of the employee handbook is being rewritten. The HR department thinks the policy on sexual harassment needs more clarity." It isn't clear and needs to be made clearer.
"We went SCUBA diving in the Cayman Islands. We could see for fifty meters. The clarity of the water was amazing." The water is very clear.
"The 'four C's' of diamond grading are color, clarity, cut, and carat weight. Diamonds have tiny internal specks or imperfections called 'inclusions.' A high clarity grade means there are very few inclusions." Even under a microscope, it looks clear.
"The essays of George Orwell are beautifully written. They are free from ornament. They are models of clarity." The writing is clear and simple.