Question

what happens when the prime minister and the president disagree about some policy ? does the view of the prime minister always prevail ?

Answer 1

when the prime minister creates a bill, the president has to sign it to pass. if he doesn't sign, it returns back for reconsideration.
the bill is reconsidered by the party members and parliament. and it is again passed. this time the president HAS to sign it no matter what.
so we can say the view of the prime minister prevail most of the time.
(Bill: when a new law is to be formed, it has to be accepted by both the sabhas and president and prime minister. then only it becomes a law.
the law before it is passed is called a bill)

Answer 2

no it is not possible to disagree prime Minster because our country is democratic country and the policy all the dicision regarding to country are discussed in parliament, lok sabha, rajya sabha