The Nuance Difference: "予定" vs "約束"

In Japanese, both 予定 and 約束 are often translated to English but have distinct usages. 予定 (よてい (yotei)) represents "plan, schedule, arrangement" (Level: N4) and typically represents Often used to talk about future plans or a set schedule. Can be used with ~がある. On the other hand, 約束 (やくそく (yakusoku)) translates to "promise, appointment, agreement" (Level: N4) and is used for Used for making promises or setting an appointment with someone. Often used with ~する. Mixing these up can sound unnatural to native Japanese speakers!