When a user utilizes the TOR network, all data is scattered within layers of nodes, and carried to the next. If ever someone tries to intercept the data sent, they’ll only be able to look into one part of it, depending on who sent it last.
For instance, when you enter the TOR network, the entry node will only be able to see your IP address since it’s the point of access. The data sent to the last node, will only be able to see the website you entered and nothing else.
However, when you use Onion Over VPN, neither will the entry node or last node trace anything back to you. This is because the TOR network, routes all traffic through a secure VPN server.