I think Adam explained it pretty well, but in case you need it in linguistic terms: "Is this person" + adjective "Does this person" + verb Examples: Is this person smart? Is this person funny? Is this person a traveler? It would not work to say: "Is this person travel?" (sorry, stupid example) Does this person like to travel? Does this person travel? It would not work to say: "Does this person smart?" (again, sorry for the stupid example) Hopefully this helps. Let me know if you need more explanation.

My understanding of the two is this. 'Is this person' is a question about a quality or feature of the person. For example, is this person happy, is this person religious or is this person kind. 'Does this person' is a question of a persons preference for interests. For example, does this person like sport, does this person drink often and does this person travel. This is my view of it although I'm sure someone else can explain it better.

but what is the difference?

Is this person alive? Does this person have a name?