What is the difference between two incarnations of the Lord?

Suppose there is a diamond with light [luster] in a glass case which is placed in a wooden box and which is placed in an iron box. [There are five entities, diamond, light or luster, glass case, wooden box and iron box. These five items are compared to the five coverings of a soul. The five coverings are Annamaya (food sheath), Pranamaya (air sheath), manomaya (mind sheath), Vijnanamaya (knowledge sheath), and Anandamaya (bliss sheath) in the outside to inside order.] The three outer boxes are respectively Annamaya, Pranamaya and Manomaya sheaths (Koshas). The first two sheaths belong to the five elements (Pancha Bhutas) and both are inseparable. The other three sheaths (Manomaya, Vijnanamaya and Anandamaya) are made of awareness and the three are inseparable. The last two sheaths are the very nature of the Lord and can never be separated (Vijnana or Jnana and Ananda). In human beings the last two sheaths are very much undeveloped. Due to this the human being knows little and enjoys very little happiness. But in the Lord, these two sheaths are infinite. Therefore the Lord knows everything and enjoys infinite bliss. Therefore in a human being, matter (the first two sheaths) and awareness (the third sheath) are only present. But in human incarnation, apart from these three sheaths the last two sheaths are also present, which are infinite. The Veda says that knowledge (Jnana) and bliss (Ananda) are the very nature of the Lord (Prajnanam Brahma, Anando Brahma). When one human incarnation changes to the other human incarnation, the first three sheaths (boxes) change but not the last two sheaths.

This means the diamond with its shine [light or luster] does not change even though the three boxes change. The shining light is the only identity for the diamond. Even the super natural powers belong to the third sheath (Manomaya) only, which consists of the three qualities (Satvam, Rajas and Tamas). This creation is a modification of the Manomaya sheath of the Lord. The last two sheaths are the nature of Nirguna Brahman. In every human incarnation, the Manomaya sheath exists but the ratio of the three qualities varies. Narasimha is furious (Rajas) and Rama is peaceful (Satvam). The first two sheaths are constant in every human incarnation.