'Out Of Moves' and 'Out Of Matches' are different losing conditions in Best Fiends.
The game is over in an 'Out Of Moves' scenario when the player has no more moves or turns left in the level. The available moves for a level are indicated by the moves counter in the top right corner of a level. The level is failed because there are no more turns available.
A game over arising from an 'Out Of Matches' situation occurs, when there is no more action to be taken in a level; for instance if there is so much slime covering the level at there is no room to make any matches (or chains), even by shuffling the pieces on the board.