SO, I am setting up dual extruders. to that end I bought two e3dv6 hotend assemblies. One (A) I paid about 90 bucks for (delivered) the other (B) I paid $20 for. One could get into the legalities and IP of the thing.... I'm no lawyer so I will not involve myself with any of that, suffice to say that the E3DV6 is a public license of some sort and the innovation in this device is invisible to me. Its a tube with a heater on the end. Like all my other tubes with heaters. As one could expect, there are bound to be differences, and there are. A is the "universal with bowden extras" B is a bowden (universal it turns out) model starting at the top Dimensionally the same length wise (as close as I can measure) A comes with a clip in bowden coupler. Hope it doesn't cause problems. I can't imagine finding another one. B has a standard pneumatic hose fitting on the top. This increases its z height about 10mm over A. Potentially limiting. The heat sinks are identical in form and finish, but not quite the same. the E3dV6 has a cone shaped chamber in the middle. B has a slightly wider cone. I believe inside these is supposed to be an empty chamber, but cannot see inside. A difference that may be because of the style of A (universal vs other style) is B has the pneumatic fitting then a small hole for the filament then into the cone and out the bottom. It appears that A has a much larger opening below the bowden fitting. Inconsequential difference in smoothness of passing filament through. But I'm so curious as to what's on the other side of the hole in B i'm tempted to drill it out. The heat breaks are NOT the same. B has a much thicker shaft/throat. At least twice the diameter. Possibly the same part as would be machined for a 3mm filament? This is a mixed blessing to me. The only time I've had a hot end failure was breaking the throat tube when trying to secure a leaky hexagon hotend. This tube will most likely be more durable. This tube will also carry more heat into the heat sink. Greater potential for heat soak/creep. B throat is slightly smaller ID. Both are well larger than the filament, but B is observably smaller both by sight and feel (inserting and moving filament around. Again, possible heat creep susceptibility. Interior finish I do not have a magnifying borescope. Under scrutiny with a 10x jewelers loop in some good light, there is no discernible difference in the interior surface. Heater block is not the same A's heater block is polished. nearly mirror. chamfered edges all the way around. B's is very rough and of slightly different dimensions. not chamfered anywhere. It is narrower and slightly taller (probably due to lack of post processing). The narrow dimension of the width causes the heater (that came with it, seems long) to stick out. Wasting valuable energy. Wiring is also not the same. Although the wires themselves appear to be similar. B comes pre-wired/pre-assembled. A comes in a baggie in pieces with no documentation or instruction. I was more than a bit let down that when paying so much for (A) a metal tube, that it didn't even come in a box or bubble package or anything. It came simply in sandwich bags with a receipt. There are a couple parts I don't even comprehend. They don't seem to be needed in my application. Of course, full assembly would lead one to possibly believe that it was ready to go. B will need disassembly and hot reassembly to prevent leaks. Have not tested yet. I have no real preference of one over the other given the evidence so far. Presenting them without the heater blocks, one would be hard pressed to determine which is the more expensive unit. Testing will tell if there is a functional difference in "real world".