Which is honest or sincere?

This is a story of a boy and a priest, right after World War II. Since the war destroyed Japan completely, nobody thought that Japan could be a big nation again. In the countryside, there was a church, and every Sunday, a boy came in order to learn English.

One day, the boy asked the priest, “Do you think some day in the future, I can go to your country and study English?” The priest thought it was an impossible dream, and said, “I don’t think so. It will take Japan a hundred years to recover.” Can we call him honest, sincere or otherwise?

Then there were another boy and priest in some other place. The boy asked the same question and the priest answered, “I’m sure that you can make it. Work hard, and your dream will come true.” The second priest thought in the same way as the first one, but wanted to cheer the boy up. Can we call him honest, sincere or otherwise?

The dictionary says, honesty means telling the truth, never stealing or cheating; not hiding the truth about something, while sincere means showing what you really think or feel, or saying only what you really think or feel.
I have always wondered whether there is any difference between honesty and sincerity, and if there is, what it is.

答えとしては、どちらもhonest でsincere ですが後者はよりpositive といえる、ということだと思います。