Window Frame itself or the Sash Frame? Do you have any pictures as I thought they were all the same size?

Like this. I’m not awesome with the exact details, I just know these are more quality windows at a better price than we are getting the contractors new construction windows for (my dad is in construction and is getting these windows pictures below at his rate from a supplier). I’m just trying to understand why on everything I’m seeing one side seems thicker.

The pictured window is probably a single sliding panel, where the stationary unit is built into the frame. On many dh's, the interior panels slides against part of the frame so the exterior (upper) panel is slightly smaller. Some companies use the same size sash stiles which results in more glass on the lower sash. Other use thicker sash stiles so that the glass aligns the same. There is no right or wrong way, and either could be considered "unbalanced" depending on perspective. Most folks don't notice a difference either way unless a sales person highlights it, but again, there's not a right or wrong answer, just pretty subjective aesthetics.