Why are xylem and phloem called complex tissues? How are they different from one another?

(N/A) Xylem and phloem are called complex tissues because they are made up of more than one type of cells that work together as a unit to perform a common function.

Xylem	Phloem
Consists of tracheids,vessels,xylem parenchyma,and xylem fibres.	Consists of sieve tubes,companion cells,phloem parenchyma,and phloem fibres.
Transports water and minerals vertically from the soil to the aerial parts of the plant.	Transports food (photosynthates) from the leaves to other parts of the plant.
Most of the cells,except xylem parenchyma,are dead at maturity.	Most of the cells,except phloem fibres,are living at maturity.