apt - Two 14.04.2 LTS installations, different kernel versions?

I have two installations of Ubuntu server 14.04.2 LTS, both installed from the same media (I just checked - the DVD used for both is still on the drive of one of them), but a couple of months apart. All packages appear to be up to date, but see the kernel version on one is higher than that on the other:

root@bud:~$ uname -r
3.13.0-55-generic

root@mud:~$ uname -r

3.16.0-40-generic

Why is this? Shouldn't I be running the 3.16 kernel on the first one?

Short answer is run

sudo apt-get install linux-generic-lts-utopic

on the first one.

But 3.13 will be supported till 14.04 EOL. For a server maybe it is better to keep it.

Or maybe it is time to run

sudo apt-get install linux-generic-lts-vivid

on both to get 3.19.

14.04.3 will come with 3.19 in about a month and support of 3.16 will come to an end a bit later.