I used to do smth and I am used to smth

 I used to do something: "I used to drink green tea."

"I used to drink green tea", means that in the past I drank green tea, but now I don't. Used to describes an action that did happen, but doesn't happen now. Check out these great examples:

"When I was young I used to play with dolls, but I don't anymore."
"Before I passed my driving test, I used to cycle everywhere."

I am used to something: "I am used to drinking green tea."

"I am used to drinking green tea" means that at first, drinking green tea was strange and unusual, but now it has become familiar. To be used to describes an action that was, perhaps, difficult and is now easy. "I am accustomed to green tea" has the same meaning.