Advisor or Adviser?

I’ve always been a little confused about the words “advisor” and “adviser”.

For one, they’re the same word except for one letter. Does that letter make a difference in what one of them means? I’ve seen it spelled both ways.

But I gotta be honest, “adviser” just … looks wrong. I don’t know what it is, but the “er” kinda makes me cringe.

Now that I’m thinking about it, it could be an issue of British v. American English. On the other hand, if that were the case, I feel like each country would have an “official” way they usually spell it. But I’ve seen it spelled both ways here in America, so that’s probably not it.

Or it could be a style thing. The AP Style Guide is what journalists use for basic writing research. It’s a “How to write News 101” handbook. How things should be spelled, referred to, and more in every type of news article under the sun.

But maybe it’s simply a question of what the various news organizations prefer. I’m not sure AP would mandate it. Can someone help me think this through?