glass 是指那种长的,上下粗细均匀或这上口略比底部口径大一小圈的玻璃杯子,这种杯子没有把手,一般用来喝牛奶和果汁等。例句:There is a glass on the table.Will you have a glass of a beer?
cup 是指有把手的杯子,一般都带有盖子,通常是做茶杯,咖啡杯来用的。Please pass me a cup of tea. Who own the cup?