Similar to mixing metals, you either embrace combining different lighting styles and finishes within a space, or just stick to one. Neither way is right or wrong, and is a matter of personal preference.
When I was shopping around for our dining room light fixture, I wanted to find something that differed from, but complimented, the light pendant in the adjacent family room. I tend to steer away from being "matchy matchy" in interior decor - light fixtures included.
Obviously, the light fixtures do NOT match whatsoever. Aside from finish, they are not even the same style. One is brass and mid-century modern, while the other is aged bronze and more transitional. Yet, despite their distinct differences, I think they pair nicely together. :)
The general simplicity of each lighting pendant is what makes the combination work. Both light pendants are "open" and rather streamlined. Although the aged bronze pendant is "enclosed", it still has the same light and airy feel as the dining room pendant since it is encased in glass. Both fixtures sport simple lines/shapes - nothing over-the-top ornate, like traditional crystal chandeliers for instance. Aged bronze and matte brass also tend to work well together since they are complimentary, muted finishes.
I am (still) on the hunt for a set of pendants to go above our kitchen island, which happens to visually connect to the dining room and family room. That means I have not one, but TWO different lighting styles to consider when coordinating the light fixtures in the kitchen. Shopping for the "right" kitchen pendants has been a good challenge, especially since my budget isn't big. :)