Ⅰ. defend “保卫、保护、捍卫”指采取积极措施以抵御或击退外来的威胁或攻击。它还可以表示“为……辩护”。如：
① It is the duty of every citizen to defend his country.保卫祖国是每一个公民的职责。
② He defended his comrades from harm. 他保护同志使其不受伤害。
③ They defended the fundamental principles of Marxism-Leninism. 他们捍卫了马克思列宁主义的基本原则。
④ He made a long speech definding his ideas. 他发表长篇演说为他的见解辩护。
Ⅱ. protect “保护”指采取措施，使之不受伤害或损害。如：
① The government protects the people’s interests. 政府保护人民的利益。
② He built a fence to protect his garden. 他围起了篱笆以保护园子。