The difference between High Capacity Filters and Standard Capacity Filters is mainly the number of pleats on a pleated filter. A High Capacity filter will have more pleats when compared to a Standard Capacity Filter in the same size and model of filter. With more pleats in a filter you are going to have more surface area to capture particles and allow air to pass through. A High Capacity Furnace Filter is a great choice but most HVAC systems won't require a High Capacity Filter and will do just fine with a Standard Capacity Filter. We always recommend using the same or a equivalent filter to the one you are currently using as all systems are different and may require specific filtration. One of the filters we carry that is available in a Standard Capacity and a High Capacity model is the Flanders Precisionaire Pre-Pleat 40.