"Would" is used as the past tense of will to talk about past habits and typical characteristics. For example, 1. The old man would sit in the corner talking to herself for hours. 2. Yesterday! He would come here. 3. When we were kids we would go playing on undays. "Used to" is also used to talk about a constant or frequent practice in the past. For example, 1. I used to be an administrative manager. 2. When I was a boy I used to like playing sport. 3. We didn't use to go out much in the winter months.

Both 'would' and 'used to' are used to talk about things that happened often in the past but don't happen anymore. We often use them to talk about things we did as children or behaviour which was typical in the past. 'My mother would read to us before we went to bed.' 'My mother used to read to us before we went to bed.' But we cannot use 'would' for habits (I 'used to' smoke not 'would') possession (I 'used to' have a dog' not 'would') or states (I 'used to' live in London not 'would') We also cannot use 'would' in the negative to talk about the past in this way because the meaning changes. 'My mother wouldn't read to us before we went to bed = she refused.