Remember the days when your manual typewriter didn’t have a key for the number 1, so you used a lowercase letter L instead? And to type an exclamation point, you typed an apostrophe first, backspaced, and then typed a period beneath it? Sure you do, punk.
AP and Chicago have very clear yet conflicting intentions, often producing diametrically opposed styles. If I think of AP as governing “fast content” (newspapers, online articles) and Chicago as governing “slow content” (books, some periodicals), you can see how the different styles grew from different needs.
I started AP vs. Chicago to keep track of style and usage according to the popular style guides The Associated Press Stylebook and The Chicago Manual of Style. A copy editor with 20-plus years of experience, I make it my job to keep up with changing styles and the evolution of language . . .