Differences between fundamental unit and derived unit

Fundamental Unit
Derived Unit

Fundamental units are all those units which are independent of any other unit (including themselves).
Derived units are all those units which are obtained by multiplying and/or dividing one or more fundamental units with or without introducing any other numerical factor.

Fundamental units cannot be further reduced to elementary level; in fact, these are elementary units.
Derived units can be reduced to its elementary level, which are composed of fundamental units.

Fundamental units cannot be expressed in terms of derived units.
Derived units can be expressed in terms of fundamental units.

Only seven fundamental units exist in Metric System or SI system.
There exist a large number of derived units in Metric System.

Examples of seven fundamental units, their abbreviation and corresponding physical properties are as follows:
 

• Length (Meter, m)
• Mass (Kilogram, kg)
• Time (Second, s)
• Temperature (Kelvin, K)
• Amount of substance (Mole, mole)
• Electric current (Ampere, A)
• Luminous intensity (Candela, cd)

Examples of few derived units along with corresponding physical properties are:
 

• Velocity (m/s)
• Acceleration (m2/s)
• Momentum (kg-m/s)
• Force (N)
• Density (kg/m3)
• Heat (J)
• Energy (J)
• Power (W), etc.

Source.