My understanding is that AliExpress was originally aimed at B2B (business-to-business) transactions. So it kind of competed more with the traditional Thomas Register – connect a business that wants to find a supplier, though in this case it took a cut on each transaction, sort of a super-distributor. But it seems to have shifted to have more of a consumer focus. Certainly the few times I’ve taken a glance, there are pretty clearly plenty of consumer-oriented things on there today. AliExpress is China-based.

I haven’t ever done more than very briefly glance at the Temu website, but from my recent reading, it and Shein – which you didn’t mention, not sure if it’s available in Australia – they’re a B2C (business-to-consumer) thing, more like Amazon. They’re aimed at the value segment. My understanding is that one major factor that contributed to Temu and Shein doing well in the US was that low-value shipments from China to the US didn’t have to pay tariffs. I’d guess that this was to help reduce the transaction cost of international sales, since any kind of red tape is going to be magnified if you have to do it many times over. So a vendor in China directly selling a pair of shoes to someone in the US didn’t have to pay a tariff. Larger-value shipments, like a bulk import of a shipping container full of shoes, did. That meant that traditional importers, who would buy a bulk shipment abroad, import it, and then have it sold split up via domestic vendors, were at a disadvantage. I don’t know whether similar factors apply to Australian customs policy. These two are China-based.

Ebay is US-based, was originally an auction site that targeted secondhand stuff. You can get new stuff there now, and not just at auction (and Amazon now sells secondhand stuff, albeit only at fixed, non-auction prices, so I’d guess that they compete more-directly with each other). I’ve only used it when looking for exotic expensive stuff that one can acquire cheaply secondhand, or stuff that can’t be found new today.