1. poem的意思是“诗”，为可数名词，可指具体的一首诗、两首诗、几首诗等;用作主语时，谓语动词的数取决于poem的数(即poem为单数，谓语动词用单数;poem为复数，谓语动词用复数)。如：

This poem is worth learning by heart. 这首诗是值得记起来的。

His poems have been compared to those of the English Romantics. 他的诗歌被拿来与英国浪漫主义诗歌相提并论。

The poem is comprehensive by me or you, but one of us may make or render it comprehensive to others.这首诗你我都能看懂,我们当中任何一个人都可以把它翻译出来,以便别人能够看懂。

2. poetry的意思也是“诗”，但为诗的总称，是不可数名词;用作主语时，谓语动词总是用单数。如：

The dancer has poetry in her movements.那舞蹈演员的动作颇有诗意。

This writer’s poetry reflects his love of nature. 该作者的诗反映出他热爱自然。

Poetry has been composed since ancient times. 从古时起人们就开始创作诗歌了。

Poetry serves to stimulate the mind. 诗歌能激发心灵。