A reef system refers to corals and other types of inverts that require specific types of light (anemones fall into this). Essentialyl Reef means a oceanic reef ecosystem, which is mostly corals and fish/inverts that live on coral reefs (but avoid fish and inverts that eat them, since you only have a limited amount and dont want to set up a $200 buffet)
Cured live rock is live rock that has already had all the organisms die off that either gets damages in shipping, or are near impossible to keep in captivity. Anything thats left varies and you wont know what is on it, hence you wont know if any lighting is needed (which is primarily for inverts that have symbiotic algae, which are mostly corals and Anemones), however if you go reef you will need good lighting.