关于there和it

除了一些固定的习惯用法 基本上是可以互换的
there be 做那有。。。的时候不要用it

没什么区别

固定句型

There 有There be句型(be动词与紧跟其后的名词决定)
It可以作形式主语，也可以作代词等等．
总之，有一定区别，但在一定条件下可以互换．如:当它们作指示代词时,可以互换:There is an apple=It is an apple.

IT 可以用于做形式主语，也可以用IT 写强调句，IT IS ……THAT……，这个句型强调的是名词（主语或宾语）的形态或用途，重点是从句（即THAT之后的句子）

THERE BE 句型是“有……”强调的是名词（主语或宾语），不是句子。

个人理解
1 it is +adj. there is +n.
2 there is+n表示存在，有
it is 表示是……
3 固定句型……
只理了些there的it的还在收集中………………

There is something wrong with…..
There is no doubt that ( of )…….
There is no need to do (for)……
There is no hurry about……
There is no(some) difficult(trouble)in…..
There is no help for…….
There is no difference between…
There is no lack of……
There is no possibility that (of)….
There is no room for………
There is no sense in…..
There is no sign of……
There is no probability that(of)….
There is no saying that……
There is no reason