CT Plan LLC is the oversight organization. Its members, the Authorizing SROs, form the Operating Committee, which holds governance authority, approves the Policies and sets the Fee Schedule.
DataCT LLC is the Independent Administrator, appointed by and acting under that oversight. DataCT is responsible for day-to-day administration: licensing, datafeed approvals, control verification, reporting, invoicing, collections and compliance.
In short: the LLC governs, DataCT administers, and the US Consolidated Tape is what the customer sees.