请问my pleasure是等于it's my pleasure吗? 就是不用谢的意思, 回答别人的thank you是吗? 而with pleasure是回答别人邀请时表达非常乐意是吗?

     【答】（it's ）my pleasure  spoken  used when someone has thanked you for doing something and you want to say that you were glad to do it 【口】别客气，不用谢 [表示乐意做某事] （摘自《朗文高级英语应试词典》第1749页）

      所以，My pleasure. = It's my pleasure.

      with pleasure  ——  used to say that you are happy to do something for someone  乐意效劳；非常愿意“Would you deliver a message for me?”“Yes,  with pleasure  ”“你可以帮我捎个信吗？”“好的，乐意效劳。”（摘自《韦氏高阶英汉双解词典》p.1585）