It's not identical hardware. The 15 was one of the most disappointing upgrades in years. It offers Less RAM (which will hinder AI features as early as next year), much weaker processor, less battery life, dimmer and smaller display, slower charging, a significantly worse camera over the 16. Not to mention the heat sink issues!
As someone who has a yearly upgrade cycle, just hold off. The 15 Pro is disappointing coming from a 14 Pro. I'd argue both the 14 and 15 years were skippable models.
The 17 Pro might offer double the RAM and significant other improvements, but most people should be fine with a 14 Pro until 2026.