The main difference is their habitat and breeding behaviour. Large species typically live outdoors in mulch, leaf litter, and damp areas. They may wander inside, particularly if drawn by moisture or food, but they are not primarily indoor pests. Addressing leaks and ventilation can help deter them. Small species are “filth” pests that thrive inside homes. They are prolific breeders, and an infestation can escalate quickly. These require professional pest control to eradicate, as they hide deep within structures and appliances.