leeward vs to leeward

leeward and to leeward both are nouns.

Word	Noun	Adjective	Verb	Adverb
leeward	Yes	Yes	No	Yes
to leeward	Yes	No	No	No

As nouns, to leeward is a hyponym of leeward; that is, to leeward is a word with a more specific, narrower meaning than leeward:

Other hyponyms of leeward include leeward side.

leeward (noun)	to leeward (noun)
the side of something that is sheltered from the wind	the side sheltered from the wind
the direction in which the wind is blowing

leeward (adjective)	to leeward (adjective)
on the side away from the wind

leeward (adverb)	to leeward (adverb)
away from the wind