AP and Chicago are mostly quite similar although AP differs in a few specific things, e.g. no Oxford comma. Where I used to work, we generally used Chicago, Mer

AP and Chicago are mostly quite similar although AP differs in a few specific things, e.g. no Oxford comma. Where I used to work, we generally used Chicago, Merriam-Webster, and IBM but we would go with AP for things like press releases because journalists generally use AP and we wanted to make it painless for them to cut and paste press releases, public company blogs, and the like.