I'll just add some points. Both verbs ("costumava" e "lia") belong to the same tense "Pretérito Imperfeito do Indicativo"; the meaning of expressions can be exactly the same (the habit of reading in the past), like "eu costumava ler NY Times todos os dias de manhã" or "eu lia NY Times todos os dia de manhã", which means "I used to read NY Times everyday in the morning" (the first form is easier, same rules of "I used to + verb in infinitive" for any verb).
The only observation is that the first form is a little more restrictive, cause it just has this meaning (you made it clear it was a habit), while in the second case you can have the same meaning of past continuous, like "eu lia NY Times quando você chegou" (I was reading NY Times when you arrived), so you have to pay attention on the context.