在充当成分上没有什么区别，都是做谓语，但是助动词，比如be will can是可以左边移的，用来直接引导疑问句和否定句，而一般的动词是不能移动的。
一般动词可以在句子中担任谓语，而助动词不行。助动词，顾名思义，是帮助实意动词的，它的作用是帮助动词构成疑问句，否定句或时态，语态。常用的助动词有 do,be, have, 和will, shall等，在使用时，要根据情况作人称和时态的变化。如：
1. Do you like sports and does your brother like sports?I didn't go to the meeting last week.注：助动词do/does/ did 帮助动词构成疑问句，否定句。
2. Li Ming has finished his homework and is playing computer games.注：助动词has 和is 分别帮助动词构成时态（完成时和进行时）The kids will have a spring outing tomorrow.注：助动词will 帮助动词构成时态（一般将来时）
3. He was very happy as he was praised by his teacher for his progress.
