Difference between Parenchyma and Collenchyma

A simple tissue is made up of one type of cell forming a homogenous or uniform mass. Parenchyma, Collenchyma and Sclerenchyma are the important simple permanent tissues found in plants.

Parenchyma is the most common type of unspecilalised simple tissue. It is composed of collection of cells which are more or less isodiametric in shape with or without intercellular space. These are the living cells with active protoplast.

Collenchyma The cells of this tissue are living cells with vacuolated protoplast. The most important distinctive character of collenchyma is that either walls are unevenly thickened or these thickenings are confined to the corners of the cells. It is usually absent in monocot.

Parenchyma vs Collenchyma

Parenchyma	Collenchyma
Parenchyma cells are present in the epidermis, cortex, pith and pericycle. Meristematic cells are parenchymatous.	It occurs in the peripheral part of elongating organs like stem and petiole, usually appearing as a continuous ring beneath the epidermis.
Thin cell wall	Unequally thickened cell wall
Intercellular space is present	Intercellular space is absent.
No pectin deposition	Pectin deposition is found at the corners.
Shape - Isodiametric	Shape - Polygonal.
Permanent tissue	Permanent tissue sometimes revives meristematic activity.
Functions: a) Storage of food materials. b) Chlorenchyma carries out photosynthesis. c) Aerenchyma helps aquatic plants in floating and gaseous exchange.	Functions:  a) It gives mechanical support. b) It can resist bending and stretching caused by winds. c) It carries out photosynthesis if chloroplast are present.