Technology varies between the platforms and the valves but essentially they achieve the same result. The goal is to deposit coating where you want it, removing the issue of masking which is required in batch processing with dip or spray booths.
The selective robot approach genuinely offers in most cases a more cost-effective solution to batch coating. The process is infinitely repatable. A far more controlled coating thickness can be achieved from board to board and from batch to batch.
Also, masking and de-masking stages can either be greatly reduced or completely eliminated. As a result, masking mistakes that typically cause expensive re-work and stripping costs, are also largely minimized or eliminated. Touch-up is also minimized after the coating process, as there is often little to no masking to be removed, causing little to no tears or lifting in the coating.
One other benefit is that less material is used. The system only sprays sufficient coating to cover the relevant areas of the board, offering another reduction in cost.