idea 最普通常用词，几乎适用于任何方面的思维活动。
concept 指从众多实例中通过概括、归纳而形成的对事物本质、全貌及其内部联系的概念或看法。
concept ion通常指个人或一些人所持有的具体概念或念头，也可指概念的形成过程，含一定的想象和感情色彩意味。
thought 指以推理、思考等智力活动为基础的心理思维活动及其结果。
notion 指的是一种模糊的，变化的莫测的想法，无可靠的基础，未经深思熟虑的观点。
impression 指外部刺激在思想中所产生的印象。
参考例句
1. The room gave an impression of decease. 这房间给人一种死亡的印象。
2. What was your first impression of London? 你对伦敦的第一印象是什么？
3. What is your first impression of Ocean Park? 海洋公园给你的第一印象是什麽？
英英解释
n.
1. a vague idea in which some confidence is placed
2. an outward appearance
3. a clear and telling mental image
4. a concavity in a surface produced by pressing
5. a symbol that is the result of printing
6. all the copies of a work printed at one time
7. (dentistry) an imprint of the teeth and gums in wax or plaster
8. an impressionistic portrayal of a person
9. the act of pressing one thing on or into the surface of another
