Total Nodes is the total number of rewardable nodes. Nodes in subnets is the total number of nodes that are active or offline in all subnets.
Here is a post from @bjoern that sheds light on why these numbers are different:
Total Nodes is the total number of rewardable nodes. Nodes in subnets is the total number of nodes that are active or offline in all subnets.
Here is a post from @bjoern that sheds light on why these numbers are different: