From what you wrote, it doesn't sound like there's much of a problem other than you not liking his general attitude. If he was actually instructing you to do s

From what you wrote, it doesn't sound like there's much of a problem other than you not liking his general attitude. If he was actually instructing you to do stuff like a manager would, that would be something. But it doesn't seem like he's doing that but rather just acting like he knows more than you. If you have overlap in your work with him where you are forced to defer to his decision-making for whatever reason, then just make your dissent known (and documented in email or something like a public meeting). If the issue is purely attitude and doesn't actually affect your work and he's not making decisions that directly affect you, then this really isn't a big deal. You can just listen and shut up and say thanks for his input and ignore him. You won't always mesh with everyone at work, that's just a part of life. And if he's not directly affecting you that's the absolute best case scenario if you don't really get along with someone. If whatever he's doing actually affects work, you can also strategically bring this up to a higher up and raise concern by saying something like "[x] is saying we need to do this, and I know he has more experience than me, but I feel strongly that the project/company would be better off doing this instead..." and explain it and make sure you are humble when doing so and acknowledge that there may be other business reasons why they haven't chosen that path that you might not be aware/privy to. But it really sounds like he's just annoying you with his attitude so I would simply ignore it and not let it get to you. Let your work speak for itself or try to befriend him since he's friends with the manager (if you want to play office politics).