Johnson vs Samuel Johnson

Johnson and Samuel Johnson both are nouns.

Word	Noun	Adjective	Verb	Adverb
Johnson	Yes	No	No	No
Samuel Johnson	Yes	No	No	No

As nouns, Johnson and Samuel Johnson are synonyms defined as:

Johnson and Samuel Johnson: English writer and lexicographer (1709-1784)

Other synonyms of Johnson include Dr. Johnson.

Johnson (noun)	Samuel Johnson (noun)
17th President of the United States; was elected vice president and succeeded Lincoln when Lincoln was assassinated; was impeached but acquitted by one vote (1808-1875)	English writer and lexicographer (1709-1784)
36th President of the United States; was elected vice president and succeeded Kennedy when Kennedy was assassinated (1908-1973)
English writer and lexicographer (1709-1784)