1 其实放不放句中不是其区别.它所修饰的词在句中所做的成分决定它是在句中还是在句末.
例：
The group ,four experts included ,was sent to investgate the incident.
The group including four experts was sent to investgate the incident.（修饰主语）
I have invited many friends ,Mary and tom included,to my birthday.
I have invited many friends to my birthday including Mary and Tom.（修饰宾语）
2 二者最主要区别是表示所修饰词的主动与被动关系
3 用逗号隔开是因为名词与名词间无相关的连接词或者是做插入语的.