Difference

Ugly
1.
very unattractive or unpleasant to look at; offensive to the sense of beauty; displeasing in appearance.

2.
disagreeable; unpleasant; objectionable: ugly tricks; ugly discords.

3.
morally revolting: ugly crime.

4.
threatening trouble or danger: ugly symptoms.

5.
mean; hostile; quarrelsome: an ugly mood; an ugly frame of mind.

6.
(esp. of natural phenomena) unpleasant or dangerous: ugly weather; an ugly sea.
Beauty
1.
the quality present in a thing or person that gives intense pleasure or
deep satisfaction to the mind, whether arising from sensory manifestations (as shape, color, sound, etc.), a meaningful design or pattern, or something else (as a personality in which high spiritual qualities are manifest).

2.
a beautiful person, esp. a woman.

3.
a beautiful thing, as a work of art or a building.

4.
Often, beauties. something that is beautiful in nature or in some natural or artificial environment.

5.
an individually pleasing or beautiful quality; grace; charm: a vivid blue area that is the one real beauty of the painting.

6.
Informal. a particular advantage: One of the beauties of this medicine is the freedom from aftereffects.

7.
(usually used ironically) something extraordinary: My sunburn was a real beauty.

8.
something excellent of its kind: My old car was a beauty.

Not really sure as to why this caught my eye. However this question came to mind....What makes the difference.