Equality of two probabilities (proportions?)

Dear R users,
I wanted to test if there is significant difference between
probabilities of the same event calculated in different ways. I am
aware about the prop.test() which does the comparison between two
proportions given the number of successes and sample sizes. But in my
case the only values I do have are the probabilities the event.

Your kind suggestions will be very appreciated.

Mamuash