Cartilage and Bone are specialised forms of connective tissue.
They are both made up of cells embedded in an extracellular matrix.
It is the nature of the matrix that defines the properties of these connective tissues.
Cartilage is thin, avascular, flexible and resistant to compressive forces. It is a strong, flexible and semi-rigid supporting tissue. It can withstand compression forces, and yet it can bend.
Bone is highly vascularised, and its calcified matrix makes it very strong. It is rigid, mainly because the extracellular matrix is calcified.