Could someone please explain to me the difference between subnet routes and
Got your question.
when we are speaking about auto-summary, all the subnetted routes (subnetting -- dividing the networks into multiple sub network's) will summarize into one single network route.
For example, In your routing table if you have multiple subnetted routes like 10.77.1.0/28,10.77.1.16/28,10.77.1.24/28 , then you can summarize into one single network route that 10.77.1.0/24.
Hope you got it.