Scarlet vs. Crimson: What's the Difference?

Scarlet

Scarlet is a brilliant red color with a tinge of orange. In the spectrum of visible light, and on the traditional color wheel, it is one-quarter of the way between red and orange, slightly less orange than vermilion.
According to surveys in Europe and the United States, scarlet and other bright shades of red are the colors most associated with courage, force, passion, heat, and joy. In the Roman Catholic Church, scarlet is the color worn by a cardinal, and is associated with the blood of Christ and the Christian martyrs, and with sacrifice.
Scarlet is also often associated with immorality and sin, particularly prostitution or adultery, largely because of a passage referring to “The Great Harlot”, “dressed in purple and scarlet”, in the Bible (Revelation 17:1–6).
Crimson

Crimson is a strong, red color, inclining to purple. It originally meant the color of the kermes dye produced from a scale insect, Kermes vermilio, but the name is now sometimes also used as a generic term for slightly bluish-red colors that are between black and rose.

Wikipedia

Wiktionary

Scarlet (adjective)

of a brilliant red colour

“a mass of scarlet berries”
Scarlet (noun)

a brilliant red colour

“papers lettered in scarlet and black”
Scarlet (noun)

scarlet clothes or material

“silk awnings of brilliant scarlet”

Crimson (adjective)

of a rich deep red colour inclining to purple

“she blushed crimson with embarrassment”
Crimson (noun)

a rich deep red colour inclining to purple

“a pair of corduroy trousers in livid crimson, they were horrid to behold”
Crimson (verb)

(of a person’s face) become flushed, especially through embarrassment

“my face crimsoned and my hands began to shake”

Oxford Dictionary

Scarlet vs. Crimson