The "forwarded service" is a completely separate service that's not tied to a residential account. You can forward all calls to that number to any domestic-PSTN or SIP destination of your choice, and it includes a bucket of incoming minutes in your monthly fee. This option is best for people who either (a) don't have a Voipo residential account, (b) already have a virtual number upgraded on their cloned line, or (c) want to use both of the 'cloned lines' on their main number.

A virtual number only rings the residential account, and usage monitoring is tied to that same account (meaning, you don't pay per minute for calls to that line, but incoming calls are part of the usage soft cap). If you upgrade the cloned line/virtual number, it can only ring to your ATA, unless you set up different forwarding rules (in which case it's a better deal than the "forwarded services" to bundle it with your Residential account). Just keep in mind that if you were to get the virtual number and want it to forward anywhere other than your Voipo main line, you have to upgrade the virtual number to the second line, and you lose the 'cloned line' feature. (For outgoing purposes, your second ATA port would be tied to the virtual number, since you would have upgraded the VN to a second line.)

I hope that makes sense. (I'm not so sure after reading it. )