My combat Viper is almost 20m/s faster than the fastest Vulture that can be built.
You were probably carrying too much junk (A rating sensors and life support, armored bulkheads, overly heavy SCB unit, etc.), but more importantly how you reacted to being confronted is what resulted in the destruction of your ship. If you had time to even attempt to talk to the guy, you had time to escape.
I always assume any CMDR interdicting me is trying to destroy me, regardless of what they do or say. I always submit to any such interdiction as fighting it will put you at a grave disadvantage if you lose the tunnel game. If my opponent seems weak or incompetent, I destroy them, if not I waste no time in fleeing (often by jumping to another system entirely).
It's the same ship whatever the mode. The Vulture is the best brawler in the game. It's as manuverable as an Eagle, has the shields of a Python, and hits like a wrecking ball...not something to be triffled with in the hands of a skilled pilot. The Viper isn't a bad ship at all, but it's woefully outclassed in durability and hitting power compared to a Vulture.