At the link here, EAC diplomatically comments on the distinction between data collected from the states and the data provided by others, such as FVAP. 

EAC’s UOCAVA Data Are:

• Official numbers provided directly by every state.
  
• Only about voters covered by the Uniformed and Overseas Citizens Absentee Voting Act (UOCAVA) as it relates to ballots sent, returned, counted and rejected.
  
• Available for all states.
  

EAC’s UOCAVA Data Are NOT

• A sampling of military and overseas voters (a subset of these total populations used to draw conclusions about the entire population).
  
• Opinion data related to whether an individual covered under UOCAVA voted or wanted to vote, or is of a particular age group or gender, for example.