S6 vs. S7 Chip
The Apple Watch Series 7 is
powered by the S7 chip, which is based around the same CPU found in the S6 chip from the Apple Watch Series 6. Such is the similarity between the chips that both CPUs have the same identifier.
Apple says that both the S6 and S7 chip provide a 20 percent performance improvement over the S5 chip in the Apple Watch Series 5 and Apple Watch SE, indicating that they have equivalent performance.
The changes in the S7 chip are more likely to relate to smaller tweaks to maintain the same "all-day" battery life with a larger display. Apple has done this before with the S5 chip, which had the same CPU as the S4 chip, simply adding a gyroscope.
The S7 chip is not a good reason to upgrade to the Apple Watch Series 7, representing a small iterative improvement rather than any noticeable performance or efficiency boost.
Article Link:
Apple Watch Series 6 vs. Apple Watch Series 7: Should You Upgrade?