Killa, nearly 40% of all grand prix wins have been from pole, and if you look at number of wins from each position down to 10, the number goes down proportionally. Naturally it's easier to win from the front. If you take wins from the front row, it's a huge percentage. Vettel has only converted 53% of his poles to wins vs 43% by Hamilton, so in that respect they aren't too different. Winning from further down the grid is considerably more difficult. Something Hamilton has been better at.
Alonso has the best pole to win conversion of all time at 65%. Alonso and Raikkonen are the only two drivers to have converted 100% poles to podiums.
The only glaring statistic to point out is that Vettel is at the top of the list with % wins from pole. I don't think he can brag too much about that. He is at the bottom of the list when you consider % wins not starting from pole. Being a young driver, two years in the fastest car on the grid helped him bolster his stats considerably. % wins from starts at 25% - shared with Senna and Prost. Ahead of them are Clark, Ascari, Schumacher and Fangio.