Leo vs Leo the Lion

Leo and Leo the Lion both are nouns.

Word	Noun	Adjective	Verb	Adverb
Leo	Yes	No	No	No
Leo the Lion	Yes	No	No	No

As nouns, Leo and Leo the Lion are synonyms defined as:

Leo and Leo the Lion: the fifth sign of the zodiac; the sun is in this sign from about July 23 to August 22

Other synonyms of Leo include Lion.

Leo (noun)	Leo the Lion (noun)
the fifth sign of the zodiac; the sun is in this sign from about July 23 to August 22	the fifth sign of the zodiac; the sun is in this sign from about July 23 to August 22
a zodiacal constellation in Northern Hemisphere between Cancer and Virgo
(astrology) a person who is born while the sun is in Leo