Hard to say when comparing Frigidaire US models
The Custom Deluxe I had (woodgrain trim, big stereo-like timer knob) had the spinner on the roof, plus the isolated tower normally reserved for the Custom Imperials. In the middle of the wash arm was the rubber diaphragm a la Whirlpool that would mate the wash arm to the tower, which spun on two sets of disc "bearings" in the lower rack.
When I fixed-up the Deluxe that Andy (RedCarpetDrew) found, I added the spinner on the top (there was an insert, but no disc) and swapped the "space-needle" spray tower with its rack gantry for the more spacious rack from the Custom Deluxe, along with a whirligig wash-arm NIB and meant for a Custom Imperial for maximum wash on an otherwise more BOL unit.
So, here, at least, the Custom Deluxe was four-level wash because it lacked the whirligig on the lower wash-arm.