Both my installs of Ubuntu 16.04 are currently 16.04.01. I have my updates set to LTS and if I change it to all updates.. the only offer is 17.10. I had problems with 16.10 so I had to reinstall 16.04 but I don't receive updates to 16.04.2 or .3 and now I am not receiving 16.04.4 update.. I have followed the instructions provided to set the 16.04 to LTS and through all updates the offer of 17.10.. I prefer to remain on 16.04 but I can't receive the updates of 16.04. This is happening on an HP AMD install and an HP Intel with an Oracle VM installed on Windows 10 on the Intel laptop Thank you Bob
This is normal
The LTS versions are supported for 5 years. Over time normal updates accumulate. So if one wants to install version 16.04 in say 2018, that is two years later, one would be faced with a large update immediately after installation.
To avoid this Canonical creates new ISO image with all the updates built in. These are called 16.04.1, 16.04.2, etc.
If you installed 16.04.1 ISO, you got all the updates in the ISO up to that point. Since then you have seen the new updates available window pop up from time to time. If you have kept your system updated either through GUI or via command line, since you installed Ubuntu, then you have all the updates that comes in the new ISO image.
The new ISO image 16.04.4 includes newer kernel and graphics stack so that it can be installed on newer computers. Since your computer does not have the CPU or GPU that came out yesterday, you probably don't need those.
Though your version of 16.04 uses an older release of kernel, that too is kept updated with security fixes through the normal update process.
So, you don't need 16.04.4.
Just keep your system up to date.
Hope this helps