Both are excellent schools and neither, based on its name alone, will have the edge over the other. As others noted above, what matters for your grad school and employment prospects is what you do with the opportunities you have as a college student.
The biggest differences will be environment – residential neighborhood (I’m told, never been) in St Paul for Mac vs. small town in Iowa (visited 4-5 times, love it). Both schools are known for being inclusive, collaborative communities. Grinnell has a more open, flexible curriculum so you don’t “have” to take anything other than the 1st year tutorial. Mac has more “traditional” gen eds requirements.