30 hours ago
I have an old VM which some years ago I upgraded from Ubuntu 14 LTS to 16. Now I've upgraded it to 18. My question is, can I assume that this installation is almost 100% identical to a freshly installed Ubuntu 18 LTS regarding the distribution, kernel, configurations etc?
In other words, should I be upgrading servers or should I be rebuilding fresh ones?
3 hours ago
There will be some differences, but most folks won't notice those differences in normal use.
Whether or not to release-upgrade or to install anew depends upon your preferences and needs. Choose the path that makes you most comfortable.
Since you are running a Virtual Machine, you have a unique opportunity to try both paths before deciding which version to keep.