Difference between Brighten and Lighten Up

BRIGHTEN vs LIGHTEN UP: VERB

To grow bright, or more bright; to become less dark or gloomy; to clear up; to become bright or cheerful.

To make bright or brighter; to make to shine; to increase the luster of; to give a brighter hue to.
To improve or relieve by dispelling gloom or removing that which obscures and darkens; to shed light upon; to make cheerful.
To make acute or witty; to enliven.

To grow bright or more bright; become less dark or gloomy: literally or figuratively.
To make bright or brighter in any manner; shed light on; make to shine; increase the luster of.
To dispel gloom from; cheer; make gay or cheerful: as, to brighten prospects.
To make illustrious or more distinguished; heighten the splendor of; add luster to.
To make acute or witty; sharpen the faculties of.
Make more cheerful through the use of color
To add brilliancy to the colors of (prints, etc.), by boiling them in a solution of soda.
(transitive; intransitive verb) To make or become bright or brighter.

Beautify, Sparkle, Shine, Enliven, Liven, Darken, Gild, Enlighten, Enhance, Illuminate, Clear, Clear up, Lighten up, Light up, Lighten

Shimmer, Dazzle, Rejuvenate, Beautify, Sparkle, Shine, Enliven, Liven, Darken, Gild, Enlighten, Enhance, Illuminate, Clear, Light up

This podcast always helps to brighten my day.
May your life continue to brighten each day.
To cause light, brighten, illuminate, enlighten, inform, civilize.
These two ingredients can help brighten white fabrics.
Loads of opportunities surely brighten the next year.
Dead Sea to smooth and brighten your skin.
They are sure to brighten up your morning.
They would brighten up a room every morning.
This pair will not only brighten your mood, it will brighten your outfit!
May your Christmas lights brighten your home, your ornaments brighten your Christmas tree, and your friend and family brighten your Christmas day.

Lighten up and introduce yourself to these little travelers.
But he was in no mood to lighten up.
Lighten up and learn to compromise on occasion.
Dude, lighten up and embrace the free publicity!
Christmas cheer that helped lighten up the screen.
Can You Lighten Up Corned Beef and Cabbage?
We must stand up against these word police and say enough is enough, lighten up people.
QUESTION so everyone should lighten up and tell me about those people up north.
Language Developing a clear style Tighten up, lighten up.
But things lighten up, as much as they can ever lighten up in the ACC, over the next three weeks.