Ubuntu Kernels and Linux Kernels have different numbers

With the recent Meltdown and Spectre security holes I've been reading on new releases of the Linux Kernel. How do I translate the latest Linux Kernel version number, say 4.15.5 to corresponding Ubuntu Kernel version numbers?

Go to this page and search on 4.15.5 and you will see:

Ubuntu Kernel Version   Ubuntu Kernel Tag     Mainline Kernel Version
4.15.0-11.12            Ubuntu-4.15.0-11.12   4.15.5

I'm not totally convinced this page is complete or updated on a timely basis but it is the closest answer I've found so far.