The fabric softener dispenser has an opening around the top of the dispenser to allow Filter-Flo water to enter the outer chamber and flush out the softener in the rinse. When it spins after wash, the softener is retained in a shallow well instead of dribbled into the washbasket, preventing staining from undiluted product. When rinse Activation begins, the softener is flushed out and into the load. This also keeps the unit from getting gunky with dried softener that is inaccessible to clean.
I've not had or seen in person the liquid detergent dispenser so can't say for sure but I suspect it works like a regular spin-out dispenser. After the prewash, the detergent is dribbled into the load and I'd imagine the water stream also keeps the bottom of that somewhat clean as well.
Obviously, you'd have to choose between detergent and softener - you can't have both in the same load without a trip back to the machine ;-)