一、解答：scary 指的是“令他人恐慌、害怕”， 与所修饰的名词或者主语之间在逻辑上有主动关系；而scared则是指“ 感到恐惧、害怕、惊恐、担心"，与所修饰的名词或者主语之间在逻辑上有被动关系。
二、关键词语解释及延伸：
scary(形容词）引起恐慌的, 胆小的, 容易受惊的, 可怕的,吓人的，恐怖的；scared （过去分词作形容词）担心的，害怕的，焦虑的，非常恐惧的，极度害怕的，吓得要死的，吓傻的。例如：
1. I think prison is going to be a scary thing for Harry. 我觉得蹲监狱对于哈里会是件很可怕的事。（ a scary thing = a thing that makes Harry fear.)
2. We watched scary movies. 我们看了几部恐怖片。(scary movies = movies which made us very afraid.)
3. This monster looks scary to me. 我觉得这个怪物看起来很可怕。( This monster makes me very afraid. )
4. Voyeurs are scary, but they are usually harmless. 偷窥狂很可怕, 但是他们通常不会伤害人。( Voyeurs make the people who are watched very afraid.)
5. I was scared that I might be sick. 我担心自己可能病了。 （I was worried by my possible illness. ）
6. I was too scared to move. 我吓得动弹不得。（Something made me too afraid to move.)
7. Margaret and Gerard cast a scared look at one another. 玛格丽特和杰勒德彼此畏怯地望了一眼。(The look suggested that Margaret and Gerard were very afraid.)
8. The street was crowded with the scared people after the earethquake. 地震发生后，街上到处是受惊吓的人。( the scared people= the people who were frightened by the earthquake.)