There are rights that you have as a member of a group that you do not have as an individual (ie., not part of the group). A union member, for example. If that was your question.
The subject was state Militias -- let's not get too far away from that.
The lower federal courts have ruled that the second amendment protects the right of individuals to keep and bear arms as members of a state Militia. That has been called by some as the "collective rights" interpretation of the second amendment.
That means that if you are not a member of a state militia, the second amendment does not protect your individual right to keep and bear arms -- THAT protection is given by your state constitution.
Militia's were merely one stated reason for individual RKBA, not the sole purpose.