There are a number of different types of paver sand which you can use to hold your slabs in place. Before purchasing the sand, you'll want to consider the pavers themselves, the ground on which you will be fitting the pavers, and also the cost of each type of sand.
This is the most common type of paver sand used by the general public. It is designed to improve the fitting of the pavers, so that they do not fall out of place. The benefits of using this kind of sand in your installation is that it is less likely to wash away during heavy rain, meaning that you have to add more to the pavers. The polymeric sand will also help you to keep the pavement in place, and it is less likely to deform.
This was once the most popular type of paver sand, but it had many disadvantages. The sand was generally placed between the pavers after fitting, and this improved the fitting of the pavers, but it had to be kept stable by adding a sealant over the top, and was often washed away during storms.