A VPN is a program which will redirect all the internet connections from your computer through a different server. If I am using push a git commit on my computer using a VPN, its internet traffic will go through the VPN before getting to the destination server. Likewise, when I try to access a website in my browser through a VPN, the information will go from the server to the VPN proxy and then finally to my computer. This is the better solution if you need your whole system to go through a proxy, with the downside that many solutions are either paid options, or are free, but have slower speeds and may contain advertisements.
With Tor, only their browser will use a proxy. If I push a commit when I have tor on my computer but not a VPN, its information will not first go through the proxy; it will go straight to the destination server. The Tor browser, however, will redirect traffic through a proxy. This is better if you only need your internet browsing to go through a proxy.
I don't believe there would be any benefit at all to running both simultaneously, and I believe that, if anything, it will slow down your connection because the information is going through more than one proxy server.
If you have other questions or need further clarification, I'd be glad to help you further!