We use "used to" to describe a repeated or continuous activity in the past that doesn't happen any more (now);
I used to play basketball. (-I don't now, but I did play regularly before)
People used to smoke on aeroplanes. (-People regularly smoked on aeroplanes before, but don't now)
Would has a bigger range of uses. It is often used in polite requests and conditional phrases.
"I'd like a cup of tea"
"Would you like something to eat?"
"If I'd studied harder, I'd be rich" (I didn't study hard, so I am not rich now)
"If I'd been kinder, she would have married me" (I wasn't kind, so we didn't get married)
You can see in these examples that would is often used for things that did not happen, whereas used to is used for things that did happen in the past.
I hope this helps,