被害 means being hurt. 被means 'being'. You can say ä»è¢«å®³ (he's being hurt). æ害 can means hurt or can mean damage(damage a car, public property). 被æ害 also means being hurt.
被害 is like, being hurt by someone or some incident, it's kind of passive, if you get what i mean. æ害 means to hurt someone, or break something, more of an active form.
被害 is being hurt, while æ害 is to hurt. i hope its not too complicated ahaha :P