Sorry for my dumb question but what is the difference between the Linux kernel at kernel.org and say the Linux kernal at Ubuntu.org? It is just different maintainers?
For example I believe the LTS version of Ubuntu runs for 5 years and you can pay for Pro support and get 10 years on their ESM version, if I understand correctly you can keep the same kernel version though the duration.
The Ubuntu kernel is downstream from the actual kernel.org version. Ubuntu just handles support of it for Ubuntu. Kernel.org are the original implementers.
Linus Torvolds and the folks at kernel.org work to continually improve the kernel and ready it for each release cycle.
Ubuntu and other distro maintainers take that work and make sure that they are shipping to you a compiled kernel(s) that dependably works with all other software on their distribution.
The other two answers are correct but missing one maker thing: many major distributions apply patches to the kernel before distributing. So there are very slight modifications.
On your final note, it's not really the same kernel version throughout, and at times they have bumped up major upstream kernel versions mid-LTS, but even disregarding that, they are constantly applying security patches (think of it as minor version increments with bugfixes from the future).
So sure, you're running kernel 5.15.0 on Ubuntu LTS 22.04, but maybe you started at 5.15.0-36 and after a few months of incremental upgrades you'll be running 5.15.0-85.
Sorry for my dumb question but what is the difference between the Linux kernel at kernel.org and say the Linux kernal at Ubuntu.org? It is just different maintainers?
For example I believe the LTS version of Ubuntu runs for 5 years and you can pay for Pro support and get 10 years on their ESM version, if I understand correctly you can keep the same kernel version though the duration.
The Ubuntu kernel is downstream from the actual kernel.org version. Ubuntu just handles support of it for Ubuntu. Kernel.org are the original implementers.
Linus Torvolds and the folks at kernel.org work to continually improve the kernel and ready it for each release cycle.
Ubuntu and other distro maintainers take that work and make sure that they are shipping to you a compiled kernel(s) that dependably works with all other software on their distribution.
The other two answers are correct but missing one maker thing: many major distributions apply patches to the kernel before distributing. So there are very slight modifications.
On your final note, it's not really the same kernel version throughout, and at times they have bumped up major upstream kernel versions mid-LTS, but even disregarding that, they are constantly applying security patches (think of it as minor version increments with bugfixes from the future).
So sure, you're running kernel 5.15.0 on Ubuntu LTS 22.04, but maybe you started at 5.15.0-36 and after a few months of incremental upgrades you'll be running 5.15.0-85.