怎样区分allusion和metonymy

allusion:
n.提及,暗示
例句与用法:
There are many humorous allusions to human foibles in the drama.
剧中多处幽默地提到人类的弱点.
His writings are full of classical allusions.
他的著作里用了很多典故.
metonymy:
n.转喻,换喻,选语失当
A word used in metonymy.
换喻词,转喻词用在换喻中的词
metaphor:
n.隐喻,暗喻
例句与用法:
She has a striking originality in her use of metaphor.
她在运用隐喻方面有独创性.
In poetry the rose is often a metaphor for love.
玫瑰在诗中通常作为爱的象征.