The word vision can imply a premonition (seeing something that you believe will happen in the future.) Ex: I had a vision that I will get into a car wreck in three days. Vision could also mean that you have a future plan, like for a company. Ex: When I began the company, I had a vision for a global market place.

To have a vision can mean the same as to have a dream, but only in certain conditions. When you sleep at night and have a bad dream, you wouldn't tell anyone, "I had a bad vision last night." When the word dream is used like in Martin Luther King Jr's famous "I have a dream speech," it means to have a vision. "I have a vision for a better future" and "I have a dream for a better future," mean the same thing.