Plagiarism is like stealing someone's work as your own without crediting.
For example, i'm a journalists, and i'm writing about an increase in dengue cases. I would have to get the numbers and data from somewhere but i submit my work without proper credits of where my data or information was taken from.
Being bias is being one-sided or unfair.
Theres a website called IGN who reviews games and movies which is known for being somewhat biased. They always seem to give good reviews of this certain company's games when the users themselves disagree and give lower ratings. A lot of people think its because this company is pretty rich.
Invasion of Privacy
An invasion of privacy is basically intruding into someone's personal life perhaps without their consent.
For example, i'm a journalist again, and it seems that theres a new popular singer. To get a good story and good pictures, i go all out to the extent of following the person and taking photos of them everywhere including inside their house.