Sullen vs Hard-hearted - What's the difference?

Sullen is a related term of hard-hearted.

is that sullen is having a brooding ill temper; sulky while hard-hearted is .

is (obsolete) one who is solitary, or lives alone; a hermit.

(er)

Having a brooding ill temper; sulky.

* Prior

And sullen I forsook the imperfect feast.

Gloomy; dismal; foreboding.

* 1593 , , IV. v. 88:

Our solemn hymns to sullen dirges change;

(Milton)

Sluggish; slow.

* Sir Walter Scott

The larger stream was placid, and even sullen , in its course.

(obsolete) Lonely; solitary; desolate.

(obsolete) Mischievous; malignant; unpropitious.

* Dryden

Such sullen planets at my birth did shine.

(obsolete) Obstinate; intractable.

* Tillotson

Things are as sullen as we are.

* sulky, morose

* cheerful * content * lighthearted * pleased

(en noun)

(obsolete) One who is solitary, or lives alone; a hermit.

(Piers Plowman)

Sullen feelings or manners; sulks; moroseness.

to have the sullens

* 1593 , , II. i. 139:

And let them die that age and sullens have;

(en adjective)