Some aircraft come with a Pilot Operating Handbook and some come with an Aircraft Flight Manual. Why the different name, and is there a difference between them?
Both a POH and an AFM meet the "Operating Limitations" requirement in the ARROW acronym.
The difference between the two is mainly in length and content: an AFM is usually a thinner document, satisfying the requirements of FAR 23.1581 and not much else, while a POH contains these required items plus other information like system diagrams (The contents & format of a POH are standardized in GAMA's Specification 1).
Parts of the POH (like the Limitations section) are FAA-Approved, and serve as the AFM, and both documents are typically associated with a specific airframe (by serial number).
A better explanation might be this:
AFM is a regulatory document (it's contents are prescribed under the section of the regulations the aircraft was certificated under - Part 23, Part 25, etc). The
POH is a GAMA-defined document whose contents meet the regulatory requirements of an AFM, and present other information in a standardized way so that a pilot can go from a Cessna to a Piper to a Mooney to a Socata and browse the book to learn about the airplane they're about to fly with all the information presented the same way no matter who the manufacturer is.
The other two types of documents you may encounter are an "Owner's Manual" (which usually goes along with a thinner AFM & provides some of the information found in the newer-style POH) and a Pilot Information Manual (PIM) which is a "generic" version of the POH which many pilots buy so they can study the procedures without removing the regulatory document from the aircraft.
Chapter 9 of the Pilot's Handbook of Aeronautical Knowledge talks a little about the differences between the two documents (and a whole lot of other flight documents).
(Posting as an answer because formatting. Quoting from the spec directly, as an FYI which some may find interesting.)
From the GAMA standard for POHs (GAMA Specification 1, rev 1996), section 0.7:
The title [of the document shall be] "Pilot's Operating Handbook and FAA Approved Airplane Flight Manual" for all airplanes except those for which the airplane manufacturer elected to provide a separate FAA Approved Airplane Flight Manual. In the latter case, the title shall be "Pilot's Operating Handbook".
Note: After the effective date of this revision, Pilot's Operating Handbooks for newly manufactured airplanes must be FAA Approved Airplane Flight Manuals.
Also of interest, since it speaks to intention, in the Preface it says,
This Specification is designed to provide guidance for the preparation of Handbooks for all types of general aviation airplanes originally certificated at maximum takeoff weights of 12,500 pounds or less
The Specification contains little, if any, new material or novel approaches. Basically, it is a guide to industry standardization of proven concepts to be presented in a form most useful to pilots.
The Federal Aviation Administration has reviewed this Specification and has ". . . determined that a handbook that would meet the specification would also meet the intent of the requirements in FAR 23, which is to provide the pilot with all of the information needed to operate his aircraft in a safe manner." The Federal Aviation Administration recognized that compliance with this Specification will result in a high degree of standardization of content and format for all aircraft types and this will lead to a level of safety equal to or higher than is required under FAR 23.
While both POH and AFM are generally used to mean the same thing, they do have some specific differences.
AFM is meant and built specific to make and model, or by serial number. In fact, while other aircraft of the same make/model can have very similar AFMs, they are usually tailored for that specific aircraft. Not only is it FAA/regulatory approved, it contains specific instructions that pilots comply to operate the aircraft safely.
POH is contains similar FAA/regulatory approved information, and should indicate certain sections of the documents are approved. For the same make and model, they generally use and refer to the same POH. Mostly used in General Aviation, the POH is also known as the standardized AFM, following the same exact format.
I'm currently training to be a CFI, and this is a pretty tough question I have to prepare to answer my students.
All the above answers are wrong. A POH is a 'kind' of AFM. All aircraft must have an approved AFM. Before 1978 this could be anything (owners manual, POH, etc.). After 1978 GAMA (General Aviation Manufacturers Association) decided to standardize the AFM around the POH format. The name POH stuck… but it is still a kind of AFM.
The POH is the official book of rules for that specific serial number airplane. The AFM is the unofficial/generic one for a type of airplane that may or may not match the one it's in. On occasion you'll run into a book labeled "AFM" that is in fact actually the "POH" (often due to an STC requirement).