“designer replica”…means designer fake

well it realy depends on the brand as to how they differ and how you can tell. selling replicas is legal i think as long as it is clear that they are replicas, and dont say the fake brand name on them. i.e you can replicate a design, say gucci, but have to make it clear that it isnt gucci, and can’t say gucci on it.

There are a few ways. For example the weight of the watch, the crown guards and the ticking of the movement! Look at this video.