yes, you are correct.
A 1000v can only take capture input on a single interface. Normal deployments would require you to to choose monitoring a vSwitch responsible for internal VM traffic or a vSwitch handling the external mirror. (It is unlikely that a customer would want to mix general VM traffic with traffic mirrored from an external source.)
A 2000v would allow you to monitor both simultaneously.
If you are monitoring a local vSwitch you will only see traffic to and from the VMs communicating though that vSwitch. (ie. Intra vSwitch traffic, traffic from a vm on the vSwitch out, and external traffic into a vm on that vSwitch)