“USED TO and WOULD are used to describe events, situations or actions that happened in the past, but don’t happen anymore.”
However, there are very significant differences between USED TO and WOULD.
1. WOULD is used when we establish the past time frame before the word would appears.
For example,
When I was a child, I would watch cartoons with my dad in the mornings.
When I was a student, I would read books in the library every Friday.
If the time frame is established after, USED TO can be used.
For example,
I used to watch cartoons with my dad in the mornings, when I was a child.
I used to read books in the library every Friday, when I was a student.
2. WOULD is not used with stative verbs (verbs that describe a state of being), such as be, understand, feel or love.
For example,
When I was a kid, I used to feel happier. درست
When I was a kid, I would feel happier. غلط
3. We cannot use WOULD when we want to talk about past state. We have to use USED TO!
For example,
I used to live in Chicago, when I was a kid. درست
I would live in Chicago, when I was a kid. غلط
So, the use of WOULD is more limited than USED TO.
Be careful when you choose which one to use. If you are really unsure, use USED TO.