Assail 僅當動詞用,而 assault 可當動詞和名詞用。就動詞而言,這兩個字有幾個意思是同義詞,包括「襲擊;攻擊」、「抨擊;嚴厲批評」及「困擾;使感到苦惱」。它們通常可以互換,甚至源自同一個古法文字 asilir,但它們的用法卻有些差異。
Assail 鮮少指 (傷害他人身體的) 暴力 (行為),而是指口頭上的攻擊,即「抨擊」,而 assault 往往指更嚴厲的批評且通常指 (傷害他人身體的) 暴力攻擊,如 While the business community has assailed the tax reform, most of the government officials have come out to support it. (儘管商業界抨擊這項稅改,但大多數政府官員都挺身而出表示支持);Police are searching for a man who used a steel pipe to assault a famous singer. (警方正在搜尋一名用鋼管攻擊一位名歌手的男子);The county magistrate was assaulted by young demonstrators. (縣長遭到年輕示威者的襲擊)。