Connectivity Volume xTb vs Connectivity Volume xMbps (flatfee)

[rickmercer]

Looking at moving server to new host because
of increasing overage charges.

Have found plans ranging with various hardware options:

Connectivity: Volume xTB
to
Connectivity: Volume xMbps (Flatfee)

Dont understand what the pros and cons are
vis a vis flatfee volume vs connectivity volume if 1Mbps ~ 320Gb.

For example, (assume hardware ~ equal) at low end can get:

10Mbps for ~ $100 per month
vs
1Tb for ~$100 per month.

Dont understand why "volume: xTB" even offered or
why anyone would get xTB over xMbps.

Explanation given, which I cant relate to is:

"Bandwidth is the highway and Datatraffic is the flow of cars using the highway. If there is 1 car, is does not matter if you have a 1-lane or 10-lane highway. However, if there are 10.000 cars on a 1-lane highway, you might want to get that 10-lane highway instead."

So which is which or ?

If someone could explain this clearer would be much appreciated...

thanks