CLS : cls is a standard for .net . cls is small set of pecification to make all languages as a .net compliant languages. cls make a use of cts and clr. if my languages (c#,vb.net,j#,vc++) wants to be compliant language it has to follow cls standard.
CTS : Common Type System is also a standard like cls. If two anguages (c# or vb.net or j# or vc++) wants to communicate with eachother, they have to convert into some common type (i.e in clr common language runtime). In c# we use int which is converted to Int32 of CLR to communicate with vb.net which uses Integer or vice versa.