It's important to know something about each one, so you can talk about them clearly.
Abuse is any act which puts another down, degrades or reduces a person's sense of self-worth.
It includes belittling, yelling, name-calling and threats. Harassment is any comment or conduct which is insulting, intimidating, humiliating, hurtful, malicious or degrading to an individual or group. It is behaviour that is repeated and unwelcome, and has a negative effect on the person it is aimed at. Be aware that it's the victim who decides if something is harassment. If you are on the receiving end, and it feels to you like harassment, then it is.