1. 词性不同
something 是复合不定代词；some things 是名词词组，some 修饰名词 things。
2. 意思不同
something 意思是“某事”“某物”；some things 的意思是“一些事”“一些东西”。
3. 语法特点不同
something 表单数概念，some things 表复数概念；形容词修饰 something 时，形容词要后置，如something new, something interesting 等，而形容词修饰some things 时，形容词应置于some 与 things 之间，如 some new things, someinteresting things等。
附例句：
▲something
This is something special. 这是一种特别的东西。
Would you like something to drink? 你喝点什么饮料好吗?
I want something to cheer me up. 我需要一点能提神的东西。
He had his camera ready, just in case he saw something thatwould make a good picture. 他把照相机准备好，万一看到什么好东西就可以拍下来。
▲some things
It’s better to leave some things unsaid. 有些话还是不说为好。
There are some things to be grateful for. 有一些事应该对之表示感激。
We have an agreement not to talk about some things. 我们有一个协议，有些事不谈。
A thief rifled through the trunk of the car and stole some things that were there. 贼匆匆翻寻了该车的行李箱，盗走了里面的东西。