Amazon Basics products have nothing to do with Ergotron, not even a licence, as far as I know. Amazon Basics likes to copy other products (there are many examples) in order to generate more sales (of course). Qualitatively, the two monitor arms are very similar, the only real difference is the accessories (e.g. another monitor arm), which are only available from Ergotron.

So, I opted for the Amzon Basic "variant" some time ago. It is exactly the same as the one from Ergotron! The actual manufacturer has left a recess by the foot and by the arm so that you can clip in the respective retailer's name with a printed plastic label. I'm glad I opted for the much cheaper of the two. It's just a pity that I had to go abroad again.