The adjective immoral means contrary to established moral principles. Immoral actions are corrupt, unethical, sinful, or just wrong. Amoral means (1) neither moral nor immoral, or (2) lacking moral sensibility. So while immoral and amoral might share a little common ground, there is a clear distinction: immoral things are bad, and amoral things are either neutral from a moral perspective or simply removed from moral considerations.
A third adjective, unmoral, means unrelated to moral considerations. The line between amoral and unmoral is blurry as well, but unmoral things (usually animals or objects) are even further removed from moral concerns than amoral things, which merely ignore morality. Unmoral often appears where immoral would make more sense.
During the Taliban regime, buzkashi was banned, as were most sports, because it was considered immoral. [Wall Street Journal]
Cocky and arrogant, McConaughey’s character thinks he’s got it all under control until a smarter, richer and truly amoral villain enters the frame. [Ottawa Citizen]
He is currently detained under degrading and inhumane conditions that are illegal and immoral. [Guardian]
Wall Street firms have always proclaimed with pride that they are amoral, merely an intermediary between buyers and sellers. [Sydney Morning Herald]
Bush had to be condemned as an immoral beast who killed women and children to get his bloody hands on Iraqi oil. [Politico]
And there’s little point in a morality tale that turns out to be flatly amoral. [New York Daily News]