Qual é a diferença entre "used to" e "would" nessas frases?

Remember: used to. You can talk about how often you used to do something.

I sometimes used to walk my dog in the park.
You usually used to go ice skating in the winter.
I often used to cook breakfast on the weekends.

Remember: would. You can talk about how often you would do something in the past.

I would sometimes walk my dog in the park.
I would always go ice skating in the winter.
I would often cook breakfast on the weekends.

Não entendi , então "used to" não está no passado ?