The skeletal numbers of lanthanides and actinides have recently been discovered, this completes the list of skeletal numbers of all the elements in the periodic table. The skeletal numbers of lanthanides and actinides have recently been utilized to analyze a limited range of chemical clusters which included sandwich complexes. Arising from this study, it became of great interest to compare and contrast the analysis of sandwich clusters of lanthanides and actinides with those of transition metal clusters. An interesting observation has been found in the analysis of lanthanides and actinides in comparison with those of transition elements. The transition metal sandwich clusters are characterized with the K(n) parameter of 0(1), while those of lanthanides and actinides are characterized with K(n) value greater or equal to 1. These analyses reveal the fact that the cluster linkages can be easily and readily determined by simple calculations using skeletal numbers. The examples included in this book amply demonstrate this concept.