The main difference between manholes and handholes is just the size of the hole. The term "manhole" refers to inspection holes installed on the laying pipes or wells of communication systems, where this hole can accommodate a person to pass through (either through or into) during inspections or maintenance of such equipment. In contrast, a handhole is smaller and only allows hands to be inserted for inspection or operation. Additionally, both manholes and handholes are not only required in communication engineering but also in large-scale systems such as HVAC (mainly central air conditioning) and power line systems, where such inspection openings are typically provided.