Kubeadm Upgrade --- apt-get vrs apt install

Trying to upgrade a test cluster from 1.11 to 1.12.0

Having trouble with apt-get

### Master
apt-get update
apt-get upgrade -y kubeadm=1.12.0
kubectl drain master --ignore-daemonsets
kubeadm upgrade apply v1.12.0
kubectl get node
apt-get upgrade -y kubelet=1.12.0
systemctl restart kubelet
kubectl get nodes

##Worker
kubectl drain worker-1
on worker-1
	apt-get upgrade -y kubeadm=1.12.0-00
	apt-get upgrade -y kubelet=1.12.0-00
	kubeadm upgrade node config --kubelet-version v1.12.0
	systemctl restart kubelet
back on Master
kubectl uncordon worker-1

First it went into an infinite loop looking for some pods. I had to Ctrl+C out of it.
Next it could not find Version ‘1.12.0-00’

The following worked better.

##instructions. These worked on Master.
apt install kubeadm=1.12.0-00  
kubeadm upgrade apply v1.12.0  
apt install kubelet=1.12.0-00

##instructions that worked on worker...
apt install kubeadm=1.12.0-00 
apt install kubelet=1.12.0-00
kubeadm upgrade node config --kubelet-version $(kubelet --version | cut -d ' ' -f 2)

Can someone explain why the second set worked.