You could check the product serial number against the online identification sites, that of course
could be faked. Also, if the computer has an OS X and is able to tell you in System Profiler or
other listing of internal hardware, a regular PC hardware would appear a bit different than Mac.
With the questionable product in your possession or close proximity for inspection, you may
find more information. If you can start it & read the information inside, much more is learned.
•How to identify your MacBook Air - Apple Support
Specifications could be cross-checked with online accessible databases, http://everymac.com
shows builds of Apple product listed and if you use an identify by serial number database, to
see what the alleged Apple or PC-fake isn't or is, that should be easy... Easier if you have it.
•Apple MacBook Air Specs (All MB/Air Technical specs) - everymac.com:
http://www.everymac.com/systems/apple/macbook-air/index-macbook-air.html
•Identify your Mac - Lookup unit by Serial Number or Model Number:
https://www.powerbookmedic.com/identify-mac-serial.php
http://www.everymac.com/ultimate-mac-lookup/
If you have downloaded the MacTracker database, it can show you more information on each
model across nearly the entire brand. http://mactracker.ca is a source for this application D/L.
How to find your Mac's model and age? - ASC user tip
Some of these sites also offer visual identification of models, where to look for in-device
serial numbers, some may be hidden or inside; others visible if unit is On, in software.
Hopefully this helps somewhat. Also an indicator may be price. If a new Apple computer or
an iDevice relies on the original owner's Apple ID and their information, it may not be worth
owning unless they transfer it. If the unit has a tie-in to an AppleID and they haven't set it
up for a new user, you may have to take the unit to an Apple Authorized service provider to
have them help set up a new owner (appleID) if you don't know how. -- And take along the
original owner whose ID set up the Mac in the first place, so they can transfer ownership.
A fake product should not need an AppleID or it may have an illegal clone on board. A fake
would probably either be a hack- in tosh or a windows pc that looks like MacBook Air. Or a
copy made by some contractor to look like a Mac. You could look into the Apple site and
check to see how to inquire deeper, in Apple Legal site. Or how to report a fake.
Good luck & happy computing! 🙂