Is the level of intelligence of a child, 4 or 5, any indication of their intelligence in the future? if a 4 yr old knows sight words & another four year only knows letters, does that mean the first child will be a better reader thus more successful?

It is not possible to state with certainty that the child recognizing words will be a better reader, because the seemingly more advanced child might have been exposed to words more frequently than the child recognizing only letters. However, if indeed both children had been exposed to the same material, the child reading words would likely be a better reader in the future.