If you take the dictionary (any one) meaning of the words "Replica" and "Counterfeit" and logically follow down the meaning of the words used in each as shown below, sadly it only muddies the water - strictly speaking half of the "authorised" works would fall into the "Counterfeit" category, most not being built by the original artist. Perhaps as Brian clearly pointed out, the biggest difference is in the intent to deceive - Fraud it is in any other terms, and that is clearly what a counterfeit is. As has been said so often in the past when this subject gets raised - If the "counterfeiter" can create a "precise, rigorous, acccurate, exact copy of an original" he should really be creating his own ! why put someone elses name on the frame it if it's that good, other than for fraud ?
Replica ; "Duplicate made by original artist ; facsimile ; exact copy.
Duplicate ; "One of two things exactly alike ; exact copy...." Original ; "Existant from the first ; initial, earliest, not imitative." Fascimile ; "Exact copy......." Exact ; "precise ; rigorous ; accurate, strictly correct...."
Counterfeit ; " Thing made in imitation ; not genuine ; to forge ; to simulate ; to resemble closely"
Imitation ; "Copy......." Genuine (not) ; "Of the original stock ; from it's original source...." Forge ;"Fabricate, invent (tale, lie) ; make in fraudulent imitation..." Simulate ; "Feign, put on ; pretend to be, wear guise of, mimic..." Resemble ;"Be like, have similarity to or some feature etc. in common.. Copy ;""reproduction of ; imitation....."
In reality, a counterfeit would be "created" by the cheapest, quickest, shortest route to resemble an original, deceiving the buyer and fraudulently acquiring their money. Not words I'd associate with quality marques, but one more suited to the criminal offence that it surely is.
BTW what happened to the chap in the North-East ? of England who was churning out the counterfeits of any marque you cared to ask for ?
Bob (big words are not my forte') Reid
Stonehaven
Scotland