CLS:Comman Language Specification. it is Subset of CTS.
CTS:Comman Type systemes. it can have different Types of Datatypes. it can be supports two types.
1)Value Type.
2)Refference type.
1)Value type: It can Allocated Memory in Stack,
Ex:int i =10;
I value goes to stored in stack memory,int,float,struct etc.
2)Refference type:It can Allocated Memory in Heap .
ex:class,object, delegate,interface,string etc.
 

CTS and CLS are major components through which the interoperablility is achived in dotnet framework.
cls specifies some set of rules for all the .net compilers.
cls stands for common language specification
CTS stands for common type system.CTS Common Type System ensures compatability between the
components that are developed in different languages