First off let me say that this is my first day using unity. I am going to start creating games all by myself, a one man team, if you will. But I have a question. How do professional video game makers make all the graphics for every object look the same. No object looks more realistic than a different object, and every thing just looks like the same graphics. I was wondering how this works so when I start texturing models that I make, there’s nothing where one object looks photorealistic and another object looks only somewhat realistic. Please help, thanks! 
They do it by having skilled modelers on their team. No one can really teach you to do that in a simple forum post. It takes years and years of experience and practice.
I’m not asking anything about modeling, I am asking about how they make graphics (textures) all the the same and how they all look the same amount of realistic/unrealistic to eachother. No one texture looks more realistic than another texture. Anyone else, please?
Practice, skill, experience - just like drewradley said. If it makes more sense to you, replace “modelers” with “artists” in the previous response.
I really do think drew’s hitting the nail on the head here. Coming from a spriting [a.k.a. pixel art] forum where several projects existed, each based on one “style” of pixel art, I know that one way people can do this is by explicitly stating what traits need to be shared from one sprite sheet to another.
The same concept applies to textures, modeling, just about anything art related. The artist(s) have a set of requirements for their texture to meet in order to fit in with the other artworks (textures) of the game. This creates what’s often referred to as a “style” (at least, from where I’ve been). Beyond that, it does definitely take experience to have that sense of a unified style beyond just checking off a list (it takes experience to simply follow the list, in most cases!).
So yea, that’s about the easiest answer there is, however unpleasant it may seem. But experience is everything in GameDev. Ironically, you kinda just have to stop worrying about it if you wanna get things done. Just go ahead and try. Look up some tutorials to get your feet wet and just try to understand how several artists get their textures on a model if you really want to learn the trade. And of course, just do it.