MotivationIn this day and age of miracle electronics at unbelievable prices from overseas manufacturers, the terms copy, clone and counterfeit get used a lot. Some of these items are incredibly popular, meaning there's a lot of money to be made. Some are open source hardware designs, making the legal situation unusual.
People seem to use these terms for emotional loading that reflects their view of the ethics more than from any concern for consistency. I'd therefore like to propose a standard for usage of terms that cover the spectrum of possibilities.
I'll comment on the legal issues as well, but avoid the ethics except for the extreme case. And in each case, provide a little buying advice.
The ClassificationsI'm going to list them from safest to riskiest buy. I'm going to illustrate with the Arduino hardware, as that's one of the most popular open source hardware designs on the market today.
I chose the Arduino because this post is for makers, and open source hardware is common in that community. It does mean that copyright issues are usually non-existent, as the creators explicitly allow anyone to use the design with relatively minor restrictions. So while clones and copies of open source hardware seldom have legal issues, that's not the case for the commercial designs that are common outside the maker community.
Second, that there are no copyright issues makes the use of these designs very common, so there are lots of them from any number of sources floating around, and I'm hoping to clarify the legal standing of those.
OriginalsThese are original designs. While it's almost impossible to create something without incorporating some prior work, the creators hopefully didn't knowingly incorporate other people's work illegally.
These should have no legal issues, though patent issues can occur in spite of the creator's best efforts. They are generally the safest buy, though the most expensive.
Here's the original Arduino Uno product page.
CopiesThese are also original designs, but have obvious features copied from an original.
If they are original designs, they shouldn't have copyright issues. They may well be considered derivative works, which would change that, but this doesn't matter if they started with an open source design.
Patent issues will be similar to other original work. These are likely to have quality similar to the original, as the creators went to the trouble to do a new design.
The SparkFun RedBoard is an example of a copy of the original Arduino. It takes advantage of more modern hardware and experience with the Uno to provide improvements.
The MonkMakesDuino is another copy, though less obviously so. It hasn't copied the physical design. In fact, abandoning the physical design is a feature of this board. But the electronics design has been copied, modified to be breadboard friendly with improvements similar to the RedBoard.
ClonesThese are not redesigns, but just use the original design.
Unless the designs are used with the creator's permission (which open source hardware like the Arduino gives by default), they are in violation of copyright law. There's potentially a noticeable drop in quality with these boards. The vendor's primary selling point is low cost, and they may substitute less expensive, lower quality components without checking how well the resulting system will work.
Here's a typical Uno clone on Amazon. I have no idea of the quality of this board, but you'll note the substantially lower cost. Based on the reviews, I'd say it's a pretty good board. Given Amazon's return policy, I'd have no problems ordering this board.
CounterfeitThese not only copy the original design, but also artwork and logos in an attempt to convince the buyer they are originals.
They are violating trademark of the creator. They're probably violating copyright as well, unless the designs are free to use. They are almost always of very low quality - the people building them have no qualms stealing from the original designers, and have no reason to treat the buyer any better.
Rather than provide an example, here's the Arduino page on spotting counterfeits with a lot of them. For the Arduino, a key for shopping online is near the bottom: look for the words "Arduino compatible" with the Arduino artwork. Those are counterfeits, and you should avoid them.
Purchase adviceIf you're not sure what you're doing, try to buy originals, or copies from people with good reputations.
Once you know what's what, the clones can be a good buy, assuming they are legal. They can cost an order of magnitude less, and if you're experimenting with them there's a lot less pain should you fry one. Even if one or two of 10 are dead on arrival and wind up trashed with no compensation, you're still ahead. They generally don't contribute back to the original creators, and you'll want to keep that in mind when deciding whether to buy a clone or the original.
If you're going to buy clones, buy from storefronts with a good return policy. But beware of storefronts that let sellers attach a product to an existing listing (I'm looking at you, Amazon). A seller can attach a counterfeit to a listing for a quality original with good reviews.
If you can't use a storefront with a good return policy, use a payment method - by which I mean credit card - that will protect your rights. This is NOT Paypal. At the very least, make the payment with such a credit card so you can get them to intervene if things go really bad.