High capacity filters have more square footage of media in them by increasing the pleat count. This gives more surface area for the air to pass through and therefore reduces static pressure. High capacity filters can be used to increase filter life or to simply reduce the static pressure. MERV 8 filters are available in a standard capacity or a high capacity but MERV 11 and 13 Filters are typically high capacity to offset the pressure drop. Some companies that have tried to cut corners and not increase the pleat count sufficiently have caused a hesitancy with some technicians to use higher efficiency filters. By using high capacity filters, you can increase the filter life span without necessarily increasing static pressure.
High velocity filters are typically needed in units with excessive air flow or a heavy dirt/ moisture load. High velocity filters typically are high capacity filters with heavier reinforcing wire and a heavier frame. These heavy duty filters are often needed in industrial application due to paint, weld smoke, oil mist or other excessive dirt loads that will cause a filter to collapse.
At Puremaxx we recommend that any time either high velocity or high capacity are needed that you get a filter with both features.