Okay, thank you for informing me! I would have never known the difference between those two types of collector/distributor roads, especially when online queries don't help at all. How could I learn such things in the future?
P.S., when I search for the reference code of such a road (i.e., IR15SCD01, which means "Interstate Route 15 Southbound Collector/Distributor Road 1"), all I get are news outlets saying "ramp from Russell Road to Blue Diamond Road is closed due to traffic or an accident," none of which actually explain this category of road. I only know about these classifications thanks to the Nevada DOT's official list/map of state-maintained highways.