No two designers are the same. This is true for any discipline you wish. Some designers are similar, some are on the spectrum of inspired-by's to copycats. But nevertheless, they are not the same.
Two main ways to differentiate between ways designers work is the fluidity of their design path. Simply put in a question: was the design the same from beginning to end (rigid) or did it take a few sharp turns along the way (fluid)?
That being said, the same designer can be able to put both types of design paths in motion. I know I did. My designs are mostly fluid, and I let my ideas go where they take me. Afterwards I cut out the things that didn't fit where the game has went, but keep them on the side for possible future use. When I have an idea clear in my head of how the game should work the design process of the first prototype is very fast. During such a rigid design I sometimes write down questions and issues that might rise during playtest but I never let them annoy me until I'm done.
A rigid design gone well is a surprising thing, especially if it works straight out in the prototype phase. It is also possible to make a rigid design into a fluid one which is very beneficial. It resonates with the notion of "get it to the table as fast as you can". Make a design the way you see it in your head for the first prototype and don't stress about issues (but do write them down), playtest it, get feedback and only then apply any fluid ideas you had.
It happened to me when I got to the table a tableau building game that has a novel action selection system. Because a dear playtester told me that a spacial element might add a competitive element to the game, it turned into a city builder (which is practically a tableau builder with adjacency). Keeping the core action selection mechanism, the cards used and the way you use them, changed to fit the new spacial element. The rigid core of the game helped me getting to the table faster, and the will to be fluid helped improve the game by means of drastically changing the actual elements of the game.
Fluid meets rigid and like it.