Parallelogram jointers are easy to fine-tune, with eccentrics at each corner of both tables. This design allows for precise adjustments without shims, and each table can be replaced individually if needed.
Dovetail jointers are less adjustable but typically require fewer adjustments over time. Grizzly dovetail jointer tables are ground flat as a matched set while mounted to the base. Because of this, replacing a single table isn't practical. Any wear adjustments would need to be made by shimming the dovetail ways.