I have been through this. My advice is nail down his ideas. Make quadruple sure you completely explain his ideas to him and get his feedback on whether you truly get his ideas.
Once you fully grasp his point of view (for real), you can determine whether there is really a conflict or not. Sometimes people are just talking about different "stages" in the startup lifecycle.
Sometimes a "product idea" quickly gets into the weeds of the "execution" and "market penetration" strategies and the "value generation" thereof. The product itself is only 20%-30% of the value a business can bring a market.
Investors are focused on "revenue" and therefore they will see things you don't. Revenue is the safety net to the risk a big player won't buy you in the future. Revenue actually multiplies that likelihood exponentially.
Be humble and passionately seek not only to fully understand their viewpoint but create a group of confident advisors to discuss everything with. I am talking about outsiders who have "more" money and success than you. Peers don't count for this part.
The stupidest thing you could do is assume you know more than the people you are asking money from. Even dumber than that is only seeking money from one investor and having a single person's viewpoint be your only sounding board. Not saying that is the case. Just an FYI point.
Keep in mind, if your vision is clearly debated out, you won't make as many mistakes and you won't fall into the pit of despair called "tunnel vision" that leads to poor "product/market" fit. If you can't win others over with your clear and simple logic, you may not know your product and/or market as well as you assume.
However, if after all of this is said and done, and you determine there is a "real" conflict, then give him high respect and validate his viewpoint and politely ask him to believe in you and the thorough due diligence you believe you have conducted.
Make sure you do this BEFORE you ask him to back you anyway with his/her money.
Do NOT lead him on thinking you are agreeing to execute on his version of your vision. That will backfire big time!