This basically means that fixes for most security vulnerabilities are not be able to be back-ported to LTS kernels but on the other side around stable releases contain all security fixes made so far.
In other words, use stable Kernels over LTS, whenever possible, assuming everything works for you and there are no specific circumstances such as working in an environment where you have no control over the Kernel - limited access etc.
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word “Linux” in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
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