In terms of yearly vs annual fee, I refer to them as being the same thing. But to be more specific find the definitions below.
annually = once every year (being what windy uses for their annual subscription)
yearly = once each year (generally a one-time payment)
So with the windy "annual" subscription (which you pay per month), you can pay
- $1.70 USD each month cancel anytime (works out to be $20.89 a year in total)
- $32.99 USD on a one time payment
I recommend checking out what the prices are that apply to you so to check that simply:
On desktop Three lines in the top left > select windy premium
In the end, I think it would pay to also check out the terms and conditions just to make sure you know what the go is.