What is the difference between aftermarket and factory service manual?
If you have automobile industry background then you might have already known these two common terms: factory service manual (FSM) and aftermarket service manual.
FSM basically stands for the manual that is published and supplied as the product of a branded company; Aftermarket service manual indicates the manual that are available separately from other brands or sources and they are used and published by other companies.
The main difference between these two manuals is where the content come from and how much information and description they provide to the reader. One comes from the OEM or Original Equipment Manufactured end while the aftermarket is from any other company such as Clinton or Haynes, or etc that is working in collaboration with the original manufacturer. Moreover the other fact to be noted is that most of the factory service manual endorse better and higher quality both in terms of content representation such schematics, layout, pictures, diagrams, and etc.
The aftermarket service manual might indicate it covers from this year to that year for a particular model, however the contents of such manual are generally not very detailed to the specific year as each model year has slightly different parts and repairing procedures. This doesn't mean aftermarket manuals don't work for you at all as it still does its job fine if you have good mechanic background or you are just performing small repair or maintenance jobs.
So, it's usually the best to go for factory service repair manual if you are going to do bigger repair or maintenance jobs on your car, because you don't want to get stuck in the middle of repair and not to know how to do next.