這兩個形容詞在意為「不滿意的」(not satisfied) 時是同義字，但在其他方面，它們並不相同。dissatisfied 意為「不悅的，不滿的，不滿意的」(displeased, discontented, or not satisfied)，通常用來形容人或其他動物：She was dissatisfied with her salary. (她對自己的薪水不滿意)；The dog seemed dissatisfied when confined to the tiny run. (這隻狗對牠被關在這麼小的地方似乎感到不滿)。就「不滿意的」意思而言，dissatisfied 要比 unsatisfied 來得常用。
Unsatisfied 意為「不滿意的，未得到滿足的」(not satisfied, not fulfilled, or left undone)，通常用來修飾情況、需求及其他無生命的事物，如 As the war continues, basic needs for many go unsatisfied. (由於戰爭持續，許多人的基本需求得不到滿足)，The appetites of the hungry refugees were left unsatisfied. (飢餓難民的胃口未獲滿足)；但 unsatisfied 也可修飾人，此時它是表示人的需求未得到充分的滿足。
Dissatisfied 和 unsatisfied 都經常跟介系詞 at、by、with 和 after 連用，如 Dissatisfied at [by, with] the filthy state of his room, he complained to the clerk at the desk. (由於對他房間的髒亂狀況感到不滿，他向櫃台員發了一段牢騷) 或 She was unsatisfied [dissatisfied] after her meal. (她對她的餐食不滿意)。dissatisfied 亦可跟 about 和 concerning 連用：My parents were dissatisfied about [concerning] the teacher’s apparent laxity in discipline. (我父母親對老師的看似管教不嚴感到不滿)。