As far as I know, here's the main difference between used to and would : used to can be used with both dynamic and stative verbs, whereas would can only be used with dynamic (action) verbs. It's a sentence I saw in a textbook: He would always know the answers.

Can we use would with stative verbs?

Would should be used only if the past time frame is established up front. ... By starting the sentence in the past, we set up the grammatical inclusion of would. 2. Would is not used with stative verbs, i.e., those that describe a state (e.g., feel, love, know) rather than an activity (e.g., run, jump, write).

What is a stative verb with examples?

Stative verbs do NOT refer to a physical action; they express a state or condition (things which are permanent; things which don't have a beginning or end). Some examples of stative verbs are: like, love, believe, know, understand, have (when it means to own), prefer, hate.