Funnels have multiple uses and therefore called differently. More or less general use is to streamline wide body of liquid into narrow neck of a vessel. During that transfer its always nice to separate any particles, sediment or precipitants during such liquid transfers. Sometimes such filtrates are waste and sometimes they are sought for and therefore different funnels are used for every purpose. Most popular funnel for short path distillation is Buchner funnel, it has dual purpose of collecting particles and clearing the liquid.