The main difference is the equipment you use in Groundwork and Work in hand.
- Groundwork is done with one rein or a single line
- Work in hand is done with two reins
Groundwork is done using a cavesson only. As you become more advanced, you can use a combination of cavesson and bit during work in hand.
Groundwork prepares the horse very well for Straightness Training at liberty.
Work in hand prepares the horse for riding, especially for the rein aids we use in riding. In work in hand you use the reins in the same way as when ridden.
In Straightness Training it's not a matter of choosing between the two, we use both, because both training components will give different dimensions to the development of your horse and both training components will strengthen each other.