CVQ = Continuously Variable Q, or in more practical terms, it means you have a knob for setting the Q, instead of a 2 or 3 position toggle switch.
Series II instruments have a CVQ pot for each filter; Series I (and anything else with a filter) use a toggle to set between no Q, and one or two other values.
When Mica says can't tell if it's a full-on Series II..., that refers to other differences between the I and II, such as extra body laminates. So in theory, you might order a Series I bass and upgrade the Q toggles to knobs.
However (and I could be wrong), as far as I know, if you ignore the construction and look at just the electronics and pickups, there are absolutely no other differences between a Series I and II, other than the toggles versus CVQs.