Hindooism vs religious belief

Hindooism and religious belief both are nouns.

Word	Noun	Adjective	Verb	Adverb
Hindooism	Yes	No	No	No
religious belief	Yes	No	No	No

As nouns, religious belief is a hypernym of Hindooism; that is, religious belief is a word with a broader meaning than Hindooism:

Hindooism: a body of religious and philosophical beliefs and cultural practices native to India and based on a caste system; it is characterized by a belief in reincarnation, by a belief in a supreme being of many forms and natures, by the view that opposing theories are aspects of one eternal truth, and by a desire for liberation from earthly evils
religious belief: a strong belief in a supernatural power or powers that control human destiny

Other hypernyms of Hindooism include faith, religion.

Hindooism (noun)	religious belief (noun)
a body of religious and philosophical beliefs and cultural practices native to India and based on a caste system; it is characterized by a belief in reincarnation, by a belief in a supreme being of many forms and natures, by the view that opposing theories are aspects of one eternal truth, and by a desire for liberation from earthly evils	a strong belief in a supernatural power or powers that control human destiny
the religion of most people in India, Bangladesh, Sri Lanka, and Nepal