核心差别
defend 强调defend 指保护某人或某物免受攻击、伤害或批评，protect 则侧重protect 指采取行动或措施来防止某人或某物受到伤害、损害或危险
使用场景对比
| 对比方面 | defend | protect |
|---|---|---|
| 核心含义 | defend 指保护某人或某物免受攻击、伤害或批评，也可表示为某人或某事进行辩护。 | protect 指采取行动或措施来防止某人或某物受到伤害、损害或危险，强调防御和保护的功能。 |
| 词性 | 动词 | 动词 |
| 使用语域 | defend 常用作及物动词，后接宾语表示保护或辩护的对象，也可与介词 against 或 from 连用表示防御的对象。 | protect 常用作及物动词，后接宾语表示被保护的对象，也可与介词 from 或 against 连用，表示保护免受某种威胁。 |
对比例句
He defended his friend when others were criticizing him unfairly.
当别人不公平地批评他朋友时，他为他辩护。
The soldiers defended the castle from the enemy attack.
士兵们保卫城堡免受敌人攻击。
Wear sunscreen to protect your skin from the sun's harmful rays.
涂抹防晒霜以保护皮肤免受太阳有害射线的伤害。
Parents should protect their children from online dangers by monitoring their internet use.
家长应通过监督孩子的上网行为来保护他们免受网络危险。
常见误用提醒
使用 defend：He defended from the attack. → He defended himself against the attack. (defend 作为及物动词时通常需要宾语，表示保护的对象；这里应加上反身代词 oneself 或具体宾语，并用 against 表示防御的对象。)
使用 defend：She defended her opinion to her boss. → She defended her opinion to her boss. (这个用法本身正确，但中文学习者常误用 defend 表示“解释”而非“辩护”；defend 强调在受到挑战或批评时的保护行为，而 explain 更中性。例如：She explained her opinion (解释) vs. She defended her opinion when challenged (辩护)。)
使用 protect：I protect my health by eating healthy food. → I protect my health by eating healthy food and exercising regularly. (错误在于 protect 通常指防止外部威胁或伤害，而健康饮食更多是促进健康，并非直接防御。正确用法应结合具体防护措施，如避免疾病或伤害，使表达更准确。)