Detroit Public Accuracy Test Revelations

The City of Detroit has 450 precincts.
Each of these precincts contains one Dominion ImageCast Precinct tabulator.
Only 14 ImageCast Precinct Tabulators were said to have been tested during Detroit Public Accuracy Test.
None of these tabulators were used during the election.

The City of Detroit has 24 tabulation workstations at their AV Counting Board.
Each of these workstations features 1 Dominion ImageCast Central tabulator.
Only one ImageCast Central tabulator was tested during the Public Accuracy Test.

What is the purpose of the Public Accuracy Test?

What is the difference between a Public Accuracy Test and a User Acceptance Test?