Tiny sacs filled with fluid, air or other such substances is known as a cyst.
Cysts can be found in skin, tissues, organs, bones, etc.
Cysts can be formed due to various underlying reasons.
Some common causes of cysts are such as injury, irritation to a hair follicle, a clogged duct in the hair follicle, ovulation, degeneration of connective tissue, etc.
Tumor:
The tumor is caused by the uncontrolled growth of dividing cells.
Tumors can also be found in tissue, skin, organs, etc.
Tumors are the oncogenic transformation of the normal dividing cells to abnormal growth.
A tumor is the result of the breakdown of cell replacement when the extra old cells continue to undergo division, it can lead to the formation of tumors.