Pixel Watch 4 (left) vs. the Galaxy Watch 9 (right) Kerry Wan/ZDNETFollow ZDNET: Add us as a preferred source on Google. Of course it's possible to mix and match and use the Samsung Galaxy Watch on a Pixel phone or the Pixel Watch on a Galaxy phone, but you'll run into a few limitations. Also: Galaxy Watch 9 vs. Galaxy Watch 8: I've compared both models, here's my adviceYou'll get a significant upgrade if you buy the smaller 40mm Galaxy Watch, and a nearly competitive battery capacity with the 44mm Galaxy Watch. You prefer a flatter designThere's a 4.6mm difference between the Galaxy Watch 9 and the Pixel Watch 4, with the Pixel Watch 4 being 12.3 mm thick and the Watch 9 8.6mm. You want standalone satellite communicationsThe Galaxy Watch Ultra 2 offers the satellite functionalities of the Galaxy lineup -- something the Watch 9 doesn't have.