The main difference is that the nature is different, the composition is different, and the role is different, as follows:
One, the nature is different
1, sieve tubes
Refers to the tubular structure in the phloem of higher plants.
2. Ducts
refers to the tubular structures in the xylem of plants that mainly transport water and inorganic salts.
Two, the composition is different
1, sieve tube
Sieve tube by a series of end-walls with sieve plate tubular living cells connected, each cell is a sieve tube molecules.
2. Ducts
are composed of a series of highly specialized tubular dead cells with perforated end walls, each of which is called a ductal molecule or ductal node.Three, different roles
1, sieve tube
Transportation of nutrients.
2. Ducts
Transport water and inorganic salts.
The above references? Baidu Encyclopedia-Sieve Tubes, Baidu Encyclopedia-Plant Conduits