That seems like a reasonable observation. The ID of my original nozzles is about 2.0mm and the new acquisitions are about 4.0mm.
Just checked the listing - and there is no mention of filament size at all.
Will message the Seller.
Which is totally normal (assuming you meant 0.2mm and 0.4mm - 4mm nozzle would be insane).
Filament diameter has nothing to do with nozzle diameter. You can use 1.75mm filament with 0.4mm nozzle the same as you can use 3mm filament. The same with 0.2mm or any other nozzle. Most printers actually come with 0.4mm nozzles, regardless of filament they use. It is a good all around size for most prints. Even 0.4mm nozzle can print 0.1mm layers, you don't need smaller nozzle for that.
Nozzle diameter affects the layer thickness you can achieve and how fast (or slow) you can print (bigger nozzle = can do faster print with thicker layers but worse details). It is up to the extruder and hotend to supply the nozzle with sufficient amount of
molten plastic to keep it going. Whether that plastic was originally a 1.75mm or 3mm diameter string is totally irrelevant as long as your extruder is designed for it and your machine settings are correct (the machine has to extrude more of a 1.75mm filament than 3mm one for the same amount of plastic).
In fact, using too small nozzles (like 0.1-0.2mm) is counterproductive because you can't print thicker layers or print fast when needed (the extruder is unable to push enough plastic through the small hole in time). Not everything needs to be printed in 0.1mm layer height (and take ages). 0.2-0.3mm layers, using 0.4mm nozzle are totally common.