Wood is a thing: the material from trees, or a small forest. Would is a verb that helps other verbs, as in "I would help". If you can swap in "will" (or "could"), you want would.
The core difference
Wood is a noun for tree material or a small forest, while would is a verb used for the past, hypotheticals and polite requests.
- wood — the material from trees, or a small forest: They chopped wood all afternoon to keep the fire going.
- would — a verb used for hypotheticals, past habits and polite requests: If I had more time, I would learn the piano.
How to tell them apart
They sound identical, so the mix-up only shows up in writing. A quick test: wood is something you can touch, such as a table, a plank or a woodland path. Would always sits before another verb, as in "would call" or "would go".
Memory trick: would has the letters of "ould", like could and should, its family of helper verbs. Wood has two o's, like the two round knots you might spot in a plank.