What is the difference between Lubuntu and Ubuntu with the LXQt desktop?
I understand that Lubuntu requires less resources, but I don't care about that - I'm on a high-end desktop that's plenty fast. I just prefer the LXQt DE.
Resource use aside, what are the differences between "real" Lubuntu and Ubuntu with LXQt?
For example, does it affect the support offered by Ubuntu Pro?
There is guaranteed support on packages found in main which include all the packages found on Ubuntu Desktop/Server etc. ISOs.
There is no guarantee on packages from universe or community supported beyond the 3 years, though all 'universe' packages can receive fixes during the normal 5 year cycle of a LTS by any MOTU, but teams offer only 3 years guaranteed support.
During the first three years of support; in my opinion there is no difference between Ubuntu with LXQt, and a Lubuntu system. You could also extend that to the full five year cycle (personally I'd call a Lubuntu system a Ubuntu system using LXQt after Lubuntu reaches EOL at the end of three years).
After LTS has ended; or after the five years though; you'll need to read the fine print of what packages are included. Canonical have published numerous 'indicators' which read like a very large number of packages; but we don't know how they are calculated. They've specified some architectures are included; some are excluded, but even with that detail, it's clear to see only a small subset of packages are included in Ubuntu Pro support guarantees.
If you're using a Ubuntu LTS release past it's five years of standard support, I'd personally opt to use the default desktop (GNOME for recent releases). This applies with 12.04 ESM, 14.04 ESM & 16.04 ESM (which used Unity 7 desktop by default). This 'opinion' is based on reading the various notices/blogs put out by Canonical on this matter.
In a number of months we'll get more details about Ubuntu 18.04 LTS as it transitions to ESM/UA support, and when the full list of packages that will receive support are available, my opinion may differ to what is now (which is based largely on prior 12.04, 14.04 & 16.04 facts). Whilst the number of packages has been increased significantly, we still don't know which packages are to be included on 18.04 and later ESM/UA support plans.
