(Used to) is used to express past events that happened in the past, the equivalent tense is simple past.
It's used in the following cases:
1- To express events that happened in the past on a regular basis: "I used to play football on Sundays."
2- To express past events that happened under certain circumstances or conditions: "He used to take long walks after rain."
3- A particular identity or profession that represented someone/something in the past + be: "I used to be a cop/ This place used to be a stadium."
As for (to be use to), it has two types:
1- To be + used + to + verb +ing is used to express habits:
I'm used to studying while listening to music.
2- To be + used + to + object pronoun (like me, him, it us etc./proper noun or noun clause (like John, Linda, Parisian food) is used to express that you're accustomed to someone/something and that you find them normal, familiar or pleasing:
I'm used to it, they're used to cold weather etc.