https://www.cnet.com/news/apple-watch-series-4-vs-series-3-which-one-should-you-buy-best/ > At first glance, both the Apple Watch Series 4 and its predecessor seem to share the same basic design: square watch face with rounded edges, swappable bands and a variety of metal finishes to choose from in two sizes. To spot the differences we need to take a closer look. > The Series 4 has a slimmer body, but its screen is actually 35 percent larger than the 38-millimeter version of the Series 3 and 32 percent larger than the larger 42mm Series 3. The screen on the Apple Watch 4 has grown to 40mm and extends almost edge to edge with rounded corners, contrasting with the thicker bezels and square corners of the Series 3. This means you'll have more finger space to type in your passcode on the 4. Plus you have more watch faces to choose from.