The difference between Cease and Lack

When used as nouns, cease means cessation, whereas lack means a defect or failing.

When used as verbs, cease means to stop, whereas lack means to be without, to need, to require.

check bellow for the other definitions of Cease and Lack

Cease as a verb (formal, intransitive):

To stop.

Examples:

"And with that, his twitching ceased."
Cease as a verb (formal, transitive):

To stop doing (something).

Examples:

"And with that, he ceased twitching."
Cease as a verb (obsolete, intransitive):

To be wanting; to fail; to pass away.

Lack as a noun (obsolete):

A defect or failing; moral or spiritual degeneracy.
Lack as a noun:

A deficiency or need (of something desirable or necessary); an absence, want.

Lack as a verb (transitive):

To be without, to need, to require.

Examples:

"My life lacks excitement."
Lack as a verb (intransitive):

To be short (of or for something).

Examples:

"He'll never lack for company while he's got all that money."
Lack as a verb (intransitive, obsolete):

To be in want.
Lack as a verb (obsolete):

To see the deficiency in (someone or something); to find fault with, to malign, reproach.