When an NCAA team plays an NAIA team in the regular season it's an exhibition game for the NAIA team, but a regular season game for the NCAA team.
Teams are starting to play NAIA teams more since the NAIA teams don't count it as a loss and instead use it as recruiting pitches and charge much less to play the game than DII teams do.
Downside, of course, is that the competition level is horrific.