Checking the Oxford English Dictionary (https://www.oed.com https://www.oed.com), and taking the first non-obsolete definition for each adjective: Complex: Con

Checking the Oxford English Dictionary (https://www.oed.com https://www.oed.com), and taking the first non-obsolete definition for each adjective: Complex: Consisting of or comprehending various parts united or connected together; formed by combination of different elements; composite, compound. Said of things, ideas, etc. Complicated: Consisting of an intimate combination of parts or elements not easy to unravel or separate; involved, intricate, confused.