Only when written 導管
General term for a tube or channel that carries fluids, gases, or cables. Often used in engineering and construction contexts.
This conduit carries gas to each household.
Various pipes are used in the factory.
Only when written 道管
Botanical term for the water-conducting cells in plants, specifically xylem vessels. Use 道管 for this sense.
In plant stems, there are xylem vessels and phloem.
General kanji spelling for conduit, pipe, or duct. Preferred when not specifically botanical.
Botanical term for vessel (xylem). Use this spelling for the plant tissue sense.
導管 is composed of 導 (guide, conduct) and 管 (pipe, tube). 道管 uses 道 (path, way) for the botanical sense. Both are Sino-Japanese compounds.