Ali Express = Straight from the Chinese factory town to to you. There are various things to watch out for. Like with electronics components the shops sell the stuff that didn’t pass quality assurance testing for whomever ordered a manufacturing run, and now the factory is selling the rejects via AE shops.

Temu = Ali Express but now with more slavery

EBay = Anyone can do eCommerce but reputation carries enough weight that at least things usually aren’t scams. A lot of it (like many amazon sellers in the US) are just middlemen for AliExpress, Temu, or similar but hopefully they get sniffed out eventually. It’s like it’s not the wild west any more because the railroad came through, but the laws between sheriffs are still real different.

I’ve spent at least $5000 on aliexpress over the past few years, maybe more. I’ve never had an issue that wasn’t resolved with a refund or a replacement. They’re pretty reliable and I’d recommend them to anyone. They stock a wide variety of components and parts if you’re building electronics or just general DIY / 3d printing / home stuff.

Temu feels way more sketchy. They try to shove more stuff down your throat, and they even have little mini games where you can try to earn free things. They’re way more about just pushing cheap shit. I tried them once, felt dirty and have never gone back.

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.

Temu is literally just a front page for AliExpress (which is itself a public/consumer front end for Alibaba), so no difference there. You’ll probably find a lot of junk and some halfway decent products.

No clue how Aussie eBay is, but here in the states it’s done a lot to clean itself up over the past decade. A few years ago, I never even considered it when online shopping because of how many dropshipping SEO-manipulating accounts there were. It was hard to find quality items from real accounts. Now, I do almost 100% of my online shopping on eBay. Mostly books, which are usually dirt cheap used.