Definite (adjective) or definitely (adverb) means certain, without a single doubt:

We have definite plans to move to New York.

(it is 100% certain that we will move there)

I'm definitely going to the party.

(it is 100% certain that I am going)

This $50 jacket is definitely overpriced. I saw the exact same jacket for $30 in another store.

(it is completely certain that $50 is too much)

The word definitively (adverb) or definitive (adjective) means that something decides an issue, or provides a clear and firm answer/solution to a particular matter:

The evidence from the DNA test definitively proved that Ryan was not the murderer.

The company had been in financial trouble for years, but its definitive end came when it declared bankruptcy in March.

Sachin 100

Century 70

Match : India V Pakistan
Venue : Bilateral test series, 2004 at Multan, Pakistan

Sehwag scored his maiden triple century and Sachin 194 as India piled up 675 in their first innings. Sachin was actually unbeaten when captain Dravid decided to declare. There was a lot of hue and cry that followed. Many were unhappy with Dravid for not giving Sachin a chance to complete his double century. India won the match comfortably.