Comparison of Underground Stems

Rhizome	Corm
The elongated thick and fleshy underground stem is called rhizome.	The thick, solid, rounded, condensed underground stem is called the corm.
It has distinct nodes and internodes.	It has much-reduced nodes and internodes.
It is formed only in a single generation.	It may form three or more generations.
Ginger is an excellent example of the rhizome.	Colocasia is an example of the corm.

Rhizome	Tuber
The elongated thick and fleshy underground stem is called a rhizome.	The swollen underground tips of branches of the vertical axis which store food and use for vegetative propagation is called stem tuber.
It does not have foliage leaves.	Tuber develops foliage leaves.
Stored food is present inside the rhizome.	Food is stored up in the tips of underground branches to form tubers.
Buds are present in the axil of scale leaves.	These are groups of lateral buds in scale leaves and are called eyes.
Eyes are absent.	Eyes are present.
An example is Ginger.	An example is potatoes.

Corm	Bulb
The thick, solid, rounded, condensed underground stem with few internodes is called the corm.	A specialized much reduced short underground stem composed of the broad conical disc is called a bulb.
They do not have fleshy leaves.	Large fleshy leaves are borne on the upper surface of the bulb.
Stored food is present.	Stored food is present in bulbs.
Buds are present in them.	They have apical and axillary buds on their upper surface.
Colocasia is an example of the corm.	Onion, garlic, etc. are examples of bulbs.