be made of表示制成成品后。Be made from表示在成品中已经无法辨认。be made of表示“由……制成”，指从原料到制成品，只发生了形状变化，没有发生本质变化，属物理变化。be made from表示“由……制成”，指从原料到制成品，发生了质的变化，已无法复原，属化学变化。
be made of与be made from的区别
Be made of和be made from都表示“由...制成”。主语为制成物，be made of表示制成成品后。Be made from表示在成品中已经无法辨认。例如：only the rough guess and estimate can be made of it。对此只能做出一个粗略的测算。
1、The desk is made of wood.（译文：桌子由木材做成。）
解析：桌子做成后还是可以看见木材，所以用be made of。
2、These cakes are made from sugar, butter and water.（译文：蛋糕由糖、黄油和水做成。）
解析：蛋糕做成后看不见糖粉，黄油或者水，所以用be made from。
be made of与be made from有什么不同
be made of”和“be made from”的使用对象不同：
1、“be made of”表示制成成品后,仍可看出原材料是什么,保留原材料的质和形状,制作过程仅发生物理变化。
如：The kite is made of paper．风筝是用纸做的。
2、“be made from”表示制成的东西完全失去了原材料的外形或特征,或原材料在制作过程中发生化学变化,在成品中已无法辨认。
如：The paper is made from wood．纸是木头做的。
be made of造句
1、The urn appeared to be made of some sort of bronze.
这瓮看起来像是某种青铜制的。
2、The pipes should be made of plastic.
这些管子应该是用塑料制作的。
3、The taps appeared to be made of solid gold.
水龙头似乎是用纯金制成的。
be made from造句
1、There's money to be made from tourism.
旅游业非常有利可图。
2、An unlimited number of copies can still be made from the original
仍可以由原件复印出无数份副本来。
3、Synthetic silk can be made from wood fibres.
人造丝可用木纤维制造。