"have visions of" can mean to have goals that you want to achieve/accomplish or it can mean to be seeing illusions/hallucinations "see visions" can also mean to see illusions or hallucinations, but you don't usually use this grammatical structure when talking about goals or dream that you wish to achieve

Context would be helpful.

"To have a vision" is to have a plan and be able to see the outcome and consequences of this plan in the future. To see visions is like having a mental image foretelling the future, for instance.