The difference between Crux and Heart and soul

When used as nouns, crux means the basic, central, or essential point or feature, whereas heart and soul means the core of a thing.

Heart and soul is also adverb with the meaning: with the utmost earnestness.

check bellow for the other definitions of Crux and Heart and soul

Crux as a noun:

The basic, central, or essential point or feature.

Examples:

"The crux of her argument was that the roadways needed repair before anything else could be accomplished."
Crux as a noun:

The critical or transitional moment or issue, a turning point.
Crux as a noun:

A puzzle or difficulty.

Examples:

"rfquotek Dr. Sheridan"
Crux as a noun (climbing):

The hardest point of a climb.
Crux as a noun (heraldiccharge):

A cross on a coat of arms.

Heart and soul as a noun:

The core of a thing; the most essential or important part.

Examples:

"The heart and soul of any democracy is its electorate."