thread is just a type of radio, similar to bluetooth or wifi
it's optimized for home automation, meaning it's robust, has low power usage, and low bandwith. since most home automation commands aren't that big, you don't need much bandwidth. It's also designed around the IP standard, so it's using the same packets that have been powering the internet for years.
every thread device that plugs in must be a repeater, so that can help with range, as devices in the middle can relay to devices further away.
it's a self healing mesh, so if a device adds or drops from your network, it will re-optimize itself. And things will find the shortest route, which is helpful for battery devices, so they can transmit at a lower power and still reach the network.
it's designed for large similtaneous number of devices, wifi will take a speed hit just from having a device connected to your network, even if that device isn't using a lot of bandwidth. which is fine if you just have a few laptops or phones on a network. But if you add 20 bulbs or sensors on top of that, it can start to bog your network down.
it uses less power than wifi or bluetooth, helpful for battery powered sensors
While it doesn't have a dedicated hub, but it does need a "border router" that's a device that has both wifi/etherent and a thread radio. HomePod minis and some appleTVs will function as a border router, but they aren't the only ones. Several of the nano leaf products are also border routers. The advantage to having multiple is redundancy, as any of them can take over if the others fail.
the connecting different vendors together is more related to Matter. Matter is a new home automation spec, think of it as a language. for controlling lights, you might need to send power state, dim level, and color. Power state is fairly easy (off or on), but for dim level, it could be called brigtness, dimmer, level, or a few other similar options, and for the actual level, it could be sent as 0-100, 1-100, 0-255, or others. This also comes into play for less straight forward things. In homekit, the thermostat mode is sent as a single number. the homekit spec says "0 is off, 1 is cool, 2 is heat, 3 is auto" . not difficult, but everyone needs to agree on what each value stands for.
Matter is the result of manufactures getting together and agreeing how to format the commands, so that every device is speaking the same language. it also includes information on how devices should discover each other, and add to the network.
Matter and thread play well together, as they were both developed around the same time, with knowledge of the other.