Why do my two Ubuntu 16.04.3 LTS machines have different kernels after updating?

I have a laptop and a desktop (lucky me!). Both are 64-bit Intel machines. I upgrade both with apt and they end up with different kernels. Why?

Desktop

$ grep -m1 name /proc/cpuinfo 
model name  : Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

$ cat /etc/lsb-release 
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.3 LTS"

$ uname -a
Linux stu 4.4.0-110-generic #133-Ubuntu SMP Fri Jan 12 18:53:57 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

Has 8 cores and 16GiB RAM.

Brought to 16.04 via an upgrade from 14.04.

Laptop

$ grep -m1 name /proc/cpuinfo 
model name  : Intel(R) Core(TM) i7-6560U CPU @ 2.20GHz

$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.3 LTS"

$ uname -a
Linux kind 4.4.0-109-generic #132-Ubuntu SMP Tue Jan 9 19:52:39 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

Has 4 cores and 16GiB RAM.

Brought to 16.04 directly--fresh install.

Update command

time (sudo apt update && sudo apt -y full-upgrade) && sudo apt-get -y autoremove --purge

I feel like I'm on two branches of an A/B test.