Remy machine aligned hair shouldn't shed more than high-end. Over processing, bad weft construction, and bad hair care generally lead to shedding.

And the country labels are indeed marketing, as hair from country X and country Y is going so be the same quality as long as it's obtained in the same way and (non-) processed in same way.

Differences come from how it's turned into extensions, and I would ask for difference such as bleachability, weight, fullness, actual properties of hair to actually know what the difference is