Work Contract, Power of Attorney Contract, Quasi-Assignment Contract
ご質問ありがとうございます。
まず「請負[契約](https://eikaiwa.dmm.com/uknow/questions/33809/)、委任契約、準委任契約」は英語で「Work Contract, Power of Attorney Contract, Quasi-Assignment Contract」と言います。
また、客契約について、説明したいなら、下記の英文になります。
Work Contract: Objective is to complete a certain work
Power of Attorney Contract: Objective is to provide services (Managed and supervised by the delegate)
Quasi-Assignment Contract: Objective is to provide services (Managed and supervised by the delegatee)
ご参考になれば幸いです。