from
https://repairpal.com/coolant-drain-vs-flushThe traditional coolant replacement process is also known as “drain and fill.” This involves simply draining the coolant at the bottom of the radiator, then topping up the radiator with fresh fluid until it it’s full. It’s quick and easy, and while it doesn’t remove all of the old coolant from your system, it is often all that’s necessary to keep your cooling system healthy.
The coolant flushing process is more complicated, and will likely be more expensive than a drain and fill.
A flush differs in the following ways:
It uses a chemical cooling system cleaner and conditioner
It uses high pressure to “power clean” your entire cooling system
It removes old coolant, dirt, rust and other deposits
Instead of letting gravity do the work, flushing uses water pressure to blast any accumulated bad stuff out of the cooling system’s passageways. Both the radiator and the engine block are cleaned out. The final step is to add new replacement coolant.
I'm not aware of any current car that has flushing in it's maintenance schedule.