past tense - "Water will boil at 100°C" and "The vine wouldn't grow"

I have read in Longman English Grammar, page No 246, that we use 'will' and 'would' to describe natural tendency

Like the simple present tense [> 9.6-8] will (with a 3rd person subject) can refer to general truths or to the qualities of things; would can sometimes refer to the past.

Water will boil at 100°C It won't boil at under 100°C

Q1: How is this sentence different from: Water boils at 100'C?

I planted a vine last year but it wouldn't grow because it didn't get enough sun.

Q 2: How is “But it wouldn't grow” different in meaning from “But it refused to grow” and “But it didn't grow”?