Two people are charged with the same crime, and one has a lot of money, and pays the best lawyers and public relations people, and gets off.

The other doesn't have any money, has a lawyer appointed for them who hasn't a clue, and who doesn't even try,and he gets banged up for life. Maybe executed, eventually.

Is that corruption? Or is corruption just people paying bribes to public officials and public officials accepting them?

Seems to me that real corruption is made up of a whole lot of different things, and straighforward cash bribery is only one of them. Giving jobs to cronies is corruption. Tying "aid" to arms deals is corruption. Putting government contracts in places where it's convenient for the next time yiou want to get elected is corruption. Telling lies to get elected is corruption. So is voting for someone because they offer you a tax-cut as a bribe, at the expense of people who are at greater need than you are.

There's a lot of it about, and I don't think it's confined to the countries that scored badly on this "survey."

Oh yes, and copywriting public domain songs, that is definitely corrupt.