Comparative Test: HP Officejet Pro 8500 vs.Samsung CLX-3175FW: Features: ADF And Duplexunit
Both AIOs feature an ADF (automatic document feed). But there are differences: For scanning and faxing HPs AIO can handle up to 50 sheets, which can be scanned automatically on both sides. The Samsung you can feed 15 sheets only, and for doublesided scans the sheets have to be turned manually.
Furthermore HPs AIO has an automatic duplexer as standard, which prints and copies both sides of a sheet. All of that is not available for Samsungs AIO.
Samsungs ADF has a substantial flaw: The lower edge of a sheet is scanned askew (see picture below).