There are a few key differences between the two.
One, the rear roller on the speed disc allows for both primary and secondary tillage, whereas an offset is suitable for only primary tillage. This means that typically two passes with a speed disc means you ready to sow. This is a significant benefit over an offset disc as a secondary implement is not required to prepare the seed bed for sowing.
Two, the actual speed of work that speed disc allows for results in a faster completion. Speed discs are capable fo working at speeds of 10 – 14 kph whereby a traditional offset disc arrangement operates at a typical speed of 6 – 8 kph.
Three. Speed discs also leave a superior seed bed when finished, resulting in a quicker establishment of crops and pastures.