look under the size there is the release and production date,most of the fake got bullshit number instead of real date..
all you gotta do is check the release date and compare to the one you got..
well,its a method,but not safe enough.so far as i know,there are three kinds of fakes ever produced:
1.the worst one,they are easy to tell,becoz they have so many key points not matched.
2.B-grade fakes (not the B-grade legit ones),they have better quality and some key points might be the same as the legit ones.but inner tags are the best way to recognize them.
3.A-grade fakes,or 1:1 grade fakes.the general looking is almost the same as the legit ones.some even have very close inside tag.
4.factory variant,they use original factory material that nike order.for example,if nike order only 1000 pairs of shoes,they will give the factory the materials for 1200 pairs,you know,there should be always some tolerance in industry,they only use 1100 pairs materials,so that means 100 pairs left,someone takes those 100pairs materials out of the factroy and produce them in un-nike-verified factory.but they usually don't come with box.they have the best quality among all fakes(they even have real air sole or zoom sole).
the 3. and 4. above all have very close inside tag,factory variants even have the same tags,so dates wouldn't be the biggest key point.