For many, if not most, federal positions, the common form of a resume as used in the private sector is not sufficient. Such resumes probably get summarily round-filed upon receipt.
The main differences between goverment resume format and the type commonly used in the private sector is that the government loves length. Lots and lots of glorious length. That “keep a resume at one page” rule is right out the window.
You have to go back a lot further in time (I want to say 15 years?) than you think you have to, and you have to give detail about every job. Time spent waiting tables is to be as fully fleshed out as time spent as CEO of Exxon (I exaggerate, but little).
You have to include a lot of minutiae about your old jobs, too – supervisor’s full name and phone number (it helps to look up an old supervisor if they’ve moved out of town or something … the feds really want to speak to them), old salary ranges (starting and ending), exact address of where you used to work, etc. On conventional resumes, you can either skip much of that, or gloss over it (e.g. just give the city of a given past employer instead of a full address).
On top of that, you have to have your name, SSN, and job position number on the top of each page of your resume. If you don’t use the automatic header tool in a word-processing program and try to do this manually, it’s easy to miss a page and have your resume summarily rejected.
I’m not sure how forthcoming USAJobs.gov is about the ticky-tack resume requirements or about the detailed narrative component that is meant to accompany the resume (NOT a cover letter). The narrative component is, internally, the “Knowledge, Skills, and Abilities” section, or “KSAs”. When these are asked for, I’m not sure if the job site gives tips that explain exactly what the hirers are looking for. The KSAs, also, are a very just-so thing that can get an applicant summarily rejected. Once you are in federal employ, there are actually classes offered on how to properly write KSAs – AFAIK, these classes aren’t offered publicly (unless a third party offers them somewhere).