In the attached picture the figure on the left is (I am 99.9% sure) a genuine IAJ001 Indiana Jones minifigure. On the right is another copy of what I initially thought was the same figure. Its isn't so easy to see in the picture so I'll list the differences here:
*Printing on the legs is lower down.
*The shirt appears to be light tan rather than very slightly blue.
*The plastic of the legs and hat are a slightly different colour.
*The pattern of crumples on the shirt doesn't quite match.
*The buckles on the belts are not shiny.
Normally a fake can be identified by the lack of LEGO logo or other identifying marks but the figure on the right has these markings:
*Body - 'LEGO' embossed at the top of the neck with the 'L' towards the front. The real one has the 'O' at the front.
*Legs - '(c)LEGO' embossed at the top running front to back. The real one has 'LEGO' running right to left. The suspected fake also has '8B' and '2B' inside the legs whereas the real just has '1' in each leg.
*Hat - '10-01' embossed on the rim. '7-01' is embossed on the real hat, although I have also seen other numbers on other hats.
I've not seen fakes before that actually go to these lengths so is it a fake or defective or something else?