Sometime means at un unknown or undecided time.
اي عند وقت غير محدد او غير معلوم في الماضي او في المستقبل ولكن لم نقرره بعد
Ex: i knew i had met her sometime. But i couldn't remember when.
Ex : please salma come to have a dinner with me sometime.
Sometimes means not often or not always.
وتعني احيانا ليس دائما او عادة.
Ex: l always played football but sometimes i played tennis.
اتمني اكون قدرت اشرح الفرق.
