Would- is used to express repeated actions in the past that do not happen now. I would climb that tree every weekend. -I would visit my Grandmother on Sunday. Used to- is used to express repeated actions in the past as well as permanent states in the past. -I used to live with my grandmother.(permanent state) I used to walk to work. (repeated) What you can't do is use "would" for repeated actions in the past. You can't say- I would live with my grandmother. -if it was a permanent state.