Would = we use ‘would’ to describe actions or situations that have been repeated again and again and again…
Used to = we use ‘used to’ for any extended action or situation in the past. Used to is more common in informal English.
So, both used to and would are used to talk about things in the past which we don’t do now or they don’t happen anymore.
Would and used to can often be used interchangeably:
When she was free, she would/ used to hum a cheerful tune.
When he was at college, he would/ used to perform in major concerts.
Bob would/ used to pay for his drinks when he was broke.
Whenever there was rain, we used to/ would tie the new saplings to a stake.
All these sentences show actions or situations in the past, which have got over now: humming a cheerful tune, performing in concerts, paying for his drinks, going to work by train – these are all finished now.
However, there are instances when would and used to cannot always be used interchangeably. When we talk about past states that have changed, we use used to and not would:
He used to live in Chicago but moved to Indianapolis.
He would live in Chicago but moved to Indianapolis. ✗ (would cannot replace used to)
Our office used to be in the New York City Center. (not would be in the …)
She used to live in Durban Central, but moved to Durban North last month. (not would live…, because living in Durban Central wasn’t repeated again and again)
Jane used to grumble to co-workers round the water cooler until she got a good raise.
There didn’t use to be a metro station here. When was it built?
The most important difference between used to and would is that would is not used with stative verbs such as love, be, understand, and feel:
When she was a kid, she used to love co-sleeping in her mom’s bed. (natural and grammatical)
When she was a kid, she would love co-sleeping in her mom’s bed. (awkward and ungrammatical)
Be careful when you are unsure about using would or used to, use used to.
Some more examples of used to:
He used to go to work by train until he had a car of his own.
We used to grow vegetables in our backyard.
We do not use ‘used to’ for events which happened suddenly or just for a moment: I used to have a fantastic idea when I sat around the camp fire. ✗
Here are some more examples of would:
When she was at hostel, she would lie in until 10 o’ clock at the weekends.
She would always forget her keys at home, until Mother threatened to punish her.
When Jane talked to her friends, Mother would eavesdrop on her phone calls.