Usually very low leakage currents. Sometimes the conducting part is metallized right onto the film and they are called metallized film capacitors. Usually large physically. Polystyrene, Teflon - Very temperature stable. Of course, there are exceptions.
Some electrolytics have better designs than others.
Others have leads designed to minimize inductance. You need a capacitor of a given value. Take a filter capacitor for a power supply. We don't care exactly what value the cap is. We just want a big one.