Does getaddr.bitnodes.io find all Bitcoin nodes or only one node per mining pool? Any ideas for finding the number of Bitcoin nodes vs the number of Bitcoin pools?

Thank you!
getaddr.bitnodes.io shows only the reachable Bitcoin nodes in the network. These are nodes that make up the core data exchanges within the P2P network.

There is non-trivial distinction between mining and non-mining nodes at the protocol level among the network participants. Although having observed the first announcement of a block from a node may be a good indicator of a mining node.

It is impossible to tell the full size of the network that includes nodes behind firewall, or nodes that only accept connection from certain IP address/netblock, or nodes that have simply hit the set max. connections.