The work machine differences are interesting. Google uses OS, browser language, and the language of content you consume as profiling signals, not just searches. If your work browsing is mostly English-language sites, Google may be slotting those accounts into a different market entirely. Same IP, but different OS telemetry, different default browser settings, different behavioral fingerprint.

Would be interesting to check myadcenter.google.com on each machine to see how different the profiles actually are.