Hinduism : 33 Crore devi-devas

Many believe that hindu religion has 33 crore (330 million) gods. The belief is based on a verse from the vedas that says aboy "33 koti" devas. The whord koti which means crore, has another meaning in sanskrit, and that is category or type.
In other words, the Vedic reference is about 33 types of Devatas, than 33 crore. They are explained in Shatpath Brahman and many other scriptures very clearly.

"Yasya Trayastri

nshad Devaa Ange Sarve Sama

ahitaa, Skamma Tam Bruhi Katamah Swideva Sah” ~ Atharva Veda

Meaning:

 With God’s influence, these thirty-three (supporting devta) sustain the world.

More on 33 comes from the number of Vedic gods explained by Yajnavalkya in Brhadaranyaka Upanishad – the eight Vasus, the eleven Rudras, the twelve Adityas, Indra and Prajapati.
(Chapter I, hymn 9, verse 2)

They are: 8-Vasu, 11-Rudra, and 12-Aaditya, 1-Indra and 1-Prajaapati.

8. Vasus ~ Earth, Water, Fire, Air, Ether, Moon, Sun, and Star. They are called Vasus, because they are abode of all that lives, moves or exists. (also mentioned in Mahabharat, 1/66/18)

11. Rudras ~ The ten Pranas (Praana, Apaana, Vyaana, Samaana, Udaana, Naag, Kurma, Krikal, Devadutta and Dhananjaya) i.e. nervauric forces which live in the human body. The eleventh is the human soul. These are called ‘Rudras’ because when they desert the body, it becomes dead and the relations of the deceased, consequently, begin to weep.

Rudra means one who makes a person to weep. { also mentioned in Harivansha 13/51-52}) 

12. Adityaas ---the twelve months of a year called Adityaas, they cause the lapse of the term of existence of each object or being. (also mentioned in Mahabharat)

1. Indra,  also known as the (all-pervading) electricity, as it is productive of great force.

1. Prajaapati, also called the “Yajna” because it benefits mankind by the purification of air, water, rain and vegetables and because it aids the development of various arts, and in it the honor is accorded to the learned and the wise.

The master of these 33 Devatas is the Mahadeva or Ishwar who alone is to be worshipped as per 14th Kanda of Shatpath Brahman.