1、词性上的区别their是形容词物主代词，后面可以接名词。

theirs是名词性物主代词，后面不能接名词2、意思上的区别their：他（她，它）们的theirs：他们的; 他的或她的。造句：

①、theirIt would cost about £ 3,000 to install a new heating system in a flat such as theirs在他们那样的一套公寓房里安装一套新的供暖系统可能要花费3,000英镑左右。Theirs had been a happy and satisfactory marriage. 他们的婚姻曾经一直幸福美满。

②、theirsThere was a big group of a dozen people at the table next to theirs 他们旁边的桌上坐了一大群人，有十几个。This child is nobody's child until someone makes her theirs officially. 在有人办理正式手续认领以前，这个孩子不属于任何人。扩展资料theypron.她们；他/她/它们；人们，大家;政府，当局。例句：They say there's plenty of opportunities out there, you just have to look carefully and you'll find them 他们说，那里机会多的是，你只要仔细找就能发现。People matter because of what they are, not what they have 人之所以重要，不在于他们拥有什么，而在于他们是什么样的人。The young horses broke in a pack, and over the first furlong, they remained in a pack. 几匹小马一起冲出，跑完头一弗隆后还没拉开距离。