healthy and healthful

[Dezi24]

What are the differences between 'healthy and 'healthful'?
I've collected example phrases and sentences (source: Space ALC:
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'healthy'
-healthy diet
-healthy recipe
-healthy exercise
-healthy posture
-eat a healthy snack
-eat junk food instead of healthy food
-Bathing in water mixed with sake is thought to be very healthy
-I have heard that red wine is considered to be healthy.

'healthful'
-healthful diet
-healthful exercise
-Blueberries are healthful
-healthful lean hamburger
-make more healthful lifestyle choices
-healthful image

But I can't rationalize the differences in use of the two.
Could anyone do it, please?

[Casiopea]

From healthy - Definitions from Dictionary.com

—Synonyms 1. hale, hearty, robust. 3. nutritious, nourishing. Healthy, healthful, salutary, wholesome refer to the promotion of health. Healthy, while applied esp. to what possesses health, is also applicable to what is conducive to health: a healthy climate; not a healthy place to be. Healthful is applied chiefly to what is conducive to health: healthful diet or exercise.

Does that help?