it sounds like a vpn. could you turn it off and on?
You wouldn't really turn TOR on and off, since it's an application rather than a background service (except in the basic sense that you would turn a normal browser on and off, by starting it, or closing it down/exiting, but that's not really what you were referring to).
So when you're running the TOR browser it doesn't affect your other regular browsers, since it's not running as a "service".
The "TOR stuff" only applies within the TOR browser....
To get a more broad / general understanding :
A VPN lets you choose your "virtual country", to access websites/content that might only be available in certain countries.
(classic example would be accessing video content for different regions, eg netflix, although netflix tries to detect VPNs and prevent this)
In theory a VPN also disguises your IP address, although some people question how much logging VPN companies do (even when they claim not to), and how much they would co-operate with law enforcement, etc....
TOR is considered to be more secure, but you don't get to "choose" your country on demand in the way you can with a VPN - it might just be "luck" as to which route through the network you happen to be assigned when using it. (Actually, I believe you can do that with TOR, but it's cumbersome, and not recommended for best security).
There are also various debates about whether it's a good idea to use a VPN and TOR at the same time, and opinions on this vary.
In (very) simplistic terms, you can view TOR as a sort of "free VPN", to give you some privacy, but without the "country selection" control feature.
If you need the "country select" feature, then you may need a VPN.
TOR is also not very good for streaming (the way it routes data over multiple connections reduces the speed).
For "regular" websites, if you already have a VPN, then using TOR may not be essential.
If you're using TOR, then you may not need a VPN.... (unless you need the country selection feature).
*However* certain websites (typically those that end in ".onion") can *only* be accessed using TOR.
So to access the "dark net", you will need to be using TOR.
Also....
As your question hints at, a VPN runs as a service, and affects *all* internet traffic to/from your computer.
So when a VPN is running, it will affect *all* browsers, including TOR (so your TOR browser will be connecting to the TOR network, via your VPN), so you get a sort of double security, although there is debate about whether this "double security" is really more secure.... Some believe it is *less* secure.
There are *many* technical details to all of this, and I'm not a "guru", so there are no doubt inaccuracies in what I've written above, and many things I've left out....