If your asking about differences on the modules themselves, the answer would be probably very little. I have no way of knowing exactly what other vendors are modifying and changing. That would be up to the vendor. I do very little to the stock Hypex design because there just isn't much you can do without some sort of tradeoff. Hypex is continually updating the modules and Bruno & Jan-Peter are more in the loop on circuit changes, design and the trade-offs of using various components.
On the power supplies, layout and other items you will find more differentiation. I use the Hypex power supplies also in many of my designs which is more expensive, but it is a total Hypex solution. I use my own transformers which I've had built and my own softstart module.
I don't know if that answers your question. I also have several models so the answer would depend upon which solution your looking at.
