Primarily it must be understood that in Hinduism the concept of God or Goddess is unlike that of monotheistic religions. The Gods of most cultures in Asia are icons of excellence to be emulated. They are not absoluteles. They may be questioned. Each represents a strength of human character. In Hinduism there are many beliefs regarding different deities. But in most of them a god is in charge. Supreme divine power in Hinduism is Para Brahman as the sole ultimate truth, an entity that exists and gives life to all things which is formless and is referred to as Vishnu or Narayana, Adi Parashakti/Shakti or Durga and Shiva or Mahadeva among different sects of Hinduism. Different forms (Avatars) of the same entity or supreme Brahman is being worshipped depending on the versatile number of traditions and sects within Hinduism.
Hindus believe all it's devi-devas are different forms of that same formless Parambrahman. Devi-Devas in Hinduism are thought as highly advanced spiritual beings and are often represented in human form or partially human and partially animal forms. Sometimes they are also represented as non-living things and plants.
The three gods who started creation: Vishnu, Brahma, and Shiva are called Bhagwans (also known as Bhagavān). Yakshas are all male gods created by the three Bhagwans.
The main god in Vaishnavite sect of Hinduism is Vishnu. Vishnu is revered as supreme Paramatman in Vaishnava tradition. Shiva is the Supreme, in Shaivite Traditions while in Shakti Traditions, Adi Parashakti is supreme. Other names such as Ishvara, Bhagavan, Bhagvati, Parmeshwara and Paramatamana also means Hindu gods and all of them mainly denote Brahman. Vishnu, Shiva and Brahma are the major gods and Lakshmi, Parvati and Saraswati are the major goddesses in Hinduism. Many Hindus believe that Brahma is the Creator, Vishnu is the preserver and Shiva or Maheshwar is destroyer.