very simple God can incarnate and does so in 6 different forms (avtars) however he/she does not go through the cycle of life and death.
the six types of avtars are as follows;
1. Ansa Avtar- his is the avtar taken by rightious kings such as Raja Janak
2. Aveshya Avtar - this is avtars with spiritual powers
3. Kala Avtar - this is avtars with extrodinary powers usually 14 or 16 powers
4. Nit Avtar - This is the Avtar taken by Sants and Mahatmas Such as Babab Ishar Singh Ji Rara Sahib Walae
5. Namit Avtar - This is where God comes to earth for a short time and does not take birth then dissappears following what work needed to be done. Examples of this are Narsingh and the future avtar of Kalki
6. Pooran Avtar - This is the most powerful Avtar of God before guru Nanak Dev Ji. It was a form which contained almost all powers. Examples of this are Ram and Krishan
However there is one Avtar Higher and that is Guru Sahib. There will never be a greater avtar that will take place.
Please listen to the first part of the Japji Sahib Katha by Giani Thakur Singh Ji on Gurmatveechar.com where this is all explained and also the divans by Sant Baba Jagjeet Singh Ji Harkhowalae which are in my folder on the gurseva hub.