1 though 3 came to be called "Nijo-jo Castle" after completion of 4 during the Edo Period, and they have also been referred to as "Kyu Nijo-jo" and "Nijo Kojo" (both meaning "old Nijo-jo Castle") in order to distinguish them from 4.
1～3について「二条城」と呼ぶのは4.が完成した江戸時代以降のことであり、4と区別する趣旨で「旧二条城」「二条古城」などと呼ばれることもある。