In a Ubuntu release version, what kinds of updates/upgrades can we (not) get on installed packages and Linux kernel?

In Debian Stable, although I haven't experienced it, I heard that the versions of installed packages and kernel can be increased. I am not sure in what sense that means. A version number usually consists of three fields. I guess it might mean we can't update or upgrade an installed package or Linux kernel in the first field, but only in in the last two fields.

In a Ubuntu LTS (e.g. Lubuntu 18.04), what kinds of updates/upgrades can we get on installed packages and Linux kernel? What kinds can't we get? In this aspect, which one is it more similar to: Debian Stable, Testing or Unstable?

In a Ubuntu non-LTS version, similar questions. In this aspect, which one is it more similar to: Debian Stable, Testing or Unstable?

Solution 1:

My currently used Ubuntu 19.04 is closest to debian-testing.

Myself, I don't think there is a debian-unstable equivalent (though having -proposed enabled on my 19.04 would be closest).

As for stable releases 18.04 LTS is closest to debian stable (but usually a year out in release, for example debian-9 release was june-2017, debian-8 was april-2015, debian-7 was may-2013, so it's not a fixed month but odd-year)

Ubuntu 16.04 LTS to debian old-stable Ubuntu 14.04 LTS is debian old-old-stable

Ubuntu LTS has the HWE kernel option; Debian has no easy switch to enable something like this. Most other updates are rather similar between Ubuntu and Debian in my opinion.

Debian has no equivalent to non-LTS releases (they release only about every second year, and have no intermediate releases).