With the AP style, abbreviations and acronyms are used only if they are common enough to be identified publicly. In that case, they can be used the second time the item is mentioned. But the first time the item is used, the words are written fully. In Chicago style, abbreviations and other acronyms are rarely used in the text, except in figures, tables, figure captions, in notes and references or within parentheses. With AP style, you write out state names in full and only abbreviate when the state is used with names of towns, cities, counties, villages or military states. With regard to mail, AP style uses abbreviations in the address, which includes the zip code, such as, "To complain about New York Commercial Bank, write to director, 345 W. 33rd St., New York, NY 1009. In headlines, AP style omits periods in abbreviations consisting of two title-case letters. On the other hand, in Chicago style, write state names in all cases. In general, AP is more apt to use abbreviations than Chicago style for things such as academic degrees, organizations and time.
In AP style, photos are identified from left to right and parentheses are used when the content in one photo is related to the rest. In Chicago style, you can describe the position of the subjects in the photos using terms such as left, right, below, above, right to left or clockwise from left. Also, with Chicago style, you should italicize these terms followed by a comma. If there are several subjects in the photo, a colon is used to separate the descriptions.
In AP style, you must use figures for all numbers greater than nine and write full alphabetical names for numbers less than 10. On the other hand, with Chicago style, you write out the names of whole numbers and fractions, for example: two, twelve, half and a third. If the whole numbers and fractions are long, you are allowed to make use of a numerical to make the expression clearer. In Chicago style, you write out names for numbers from one through 100 in all nonscientific writing. For example: One hundred people were present in the seminar. Two people died in the plane crash. The same principles are true with ordinal numbers. In AP style, you write full alphabetical names for ordinal numbers from one to nine when stating in a location-based sequence. On the other hand, Chicago style allows you to write full alphabetical names of one to one hundred, such as 100th is spelled as one hundredth.
In Chicago style, you use serial commas to separate terms or items in a series of three, including before the conjunction. For example: blue, green, and white. He opened the door, looked in, and closed it. Additionally, when a conjunction joins the last two elements in a series, use a serial comma before the conjunction. For example: attending the seminar were Alice, Margaret, and Fredrick. We have a choice of California, Texas, or Ohio. The Chicago manual style adds that, in a series of short independent clauses, the last two that are joined by a conjunction should have a serial comma between the clause and before the conjunction. Example: Jane presented the proposal to the attorney general, the attorney general discussed it with the senator, and the senator handed it to the president. On the other hand, the AP manual of style does not use the serial comma unless one of the elements in the list is a compound.