Learning about the major forms of the Divine in Hinduism may, at times, become confusing for non-Hindus, especially because the hierarchy  may differ, depending on whom you ask. Contrary to propagated belief, the number of forms of the Divine in mainstream Hinduism is small. Contemporary Hinduism basically revolves around Rama/Krishna/Vishnu, Shakti (the Mother Goddess), and Shiva. The forms of God you would most likely meet in Hindu temples, Epics and Puranas, and literature by devotional saints are listed on the chart below (click on the chart to view it).
(Feminine forms of God are shown in purple font; masculine forms are in saffron font. Names of the divine couples are underlined.)
You must have noted that the chart above is Shakti-centric, where the dotted lines show the three primary forms of Shakti. For a Vaishnava, this chart would be made differently. The following is a Sita-Rama-centric chart showing the same forms of the Divine:
Now, you can visualize how a chart for devotees of Parvati-Shiva or Lakshmi-Vishnu would look like.
 Though many Hindus believe in a hierarchy, others understand that all the divine forms are the same Brahman.