Version 15.#### (Here, 18.104.22.168.4276) is the Driver Package version number. It contains 2 drivers - Intel Graphics driver and Intel Display Audio driver. Version for the Intel Graphics driver is 10.18.10.4276, and the Intel Display Audio driver is 22.214.171.12454. I do understand how this can easily lead to a few misunderstandings.
If you check the Installation_Readme.txt bundled with these driver packages, you can check this towards the top of the text file.