There are no telltale signs, rather there are huge signs. Picture 6 tells you the whole story. On the older TM style AEG-s you can see that the gas block and the front of the gas tube up to the point it touches the upper hand-guard is molded from one piece. That is the old TM design. On image 6 You can see, that the gas tube is actually a tube that connects to the gas block. That is a huge advertisement of being a VFC copy.
As for other clues: On image 7 You can see, that the front assembly is held to the receiver by a thick pin, which is also a sign of being a VFC copy.