The entire system would be called “ductless mini-split”. It has multiple components: an outdoor inverter compressor heat-pump, the refrigerant line sets, the indoor head units.
You’re correct that you could hook up one of those outdoor inverter compressor heat pumps to a line set that actually connected to a ducted air-handler with coil inside the home. In that case, you wouldn’t have a ductless mini-split system. You would have a forced-air heat pump system.
There are also other kinds of heat pumps. The most common ones that people associate with ductless mini-splits are called air-to-air, they also make air to water, water to air, and even water to water heat pumps.
A “heat pump” works like a refrigerator, except the inside of the “fridge” is your whole house. It acts as an A/C like a fridge cools its contents. If you run the refrigerant lines in reverse, it heats your house just like the fridge generates heat on the back and sides as it cools.
That Trane unit seems to only operate in cooling mode. It might also be a single zone system — which really just means only connectors for a single line set — which would mean it’s meant to be used with an air handler and coil inside the home. But it’s really fundamentally the same in terms of the physics of the LG heat pumps that you would normally use with a mini-split system.