signal和sign的寄义差别、词性差别、用法差别。Sign的意思是迹象、标记、暗号、手势、指示牌、签署、签名、表示；signal的意思是旌旗灯号、灯号、引火线、标记、用旌旗灯号告诉、透露表现、显著的、作为旌旗灯号的、发旌旗灯号等。sign在句中既可以作名词也能够作动词；signal在句中既可以作名词，也能够作动词和形容词。
sign凡是用作数学标记、物理标记等。signal就是一种向过程传送信息的体式格局，可以将旌旗灯号想象成大楼的办理员往房间的信箱里塞小纸条。
He signaled the waiter to bring the menu.
他做手势要侍者拿菜单来。
The conductor signaled the orchestra to rise.
指挥打手式让乐队起立。
Jim signaled his helplessness to Mary to leave the party.
吉姆无法从宴会脱身时，他向玛丽使了个眼色，透露表现迫不得已。
She had a silver peace symbol hanging on a chain around her neck.
她有一个银制的和平标记挂在项链上。
She put her finger to her lips as a sign to be quiet.
她将手指放在唇上透露表现应安静。
He gave his wife a ring as a token of his love.
他给他爱人一枚戒指，作为爱情的象征。