From the Wikipedia page, the most useful paragraph in describing the differences is probably the second paragraph under "Western vs. Eastern social business relations": https://en.wikipedia.org/wiki/Guanxi#Western_vs._Eastern_soc...
It's useful because it uses a framework for understanding relationships in either culture: trust, bonding, reciprocity, and empathy. Western guanxi and Chinese guanxi can be understood through this framework. While I'm open to the idea that it's a flawed framework, it proves my point that Western culture has analogous social expectations. Less like beet sugar and aspartame and more like bat wings and bird wings - both shaped differently, both used differently, but for the same function. I am interested in the differences, but there will be a fair amount of structural similarities.
I also disagree with your characterization of this perspective as being "very western." Considering guanxi as something fundamentally different from how Western culture works is Eurocentric - very Western, as you had said. Stepping back and analyzing how informal Western reputation systems work in the same light as how guanxi works in China is a way of de-centering the Western perspective and removing the exoticism from Chinese culture.