An inductor is also an coil n a resistor is also a coil....then how it perfprms different action? why inductor?

An inductor is designed so that the resistance and capacitance is at a minimum.

A resistor is designed so that the resistance is correct and the inductance and capacitance is at a minimum.

All real parts have resistance, inductance, and capacitance. In most cases the unwanted parameters are so small that their values can be neglected. It's only at the high RF frequencies that they all have to be taken into account. That is one reason that RF design is so difficult, and gets worse as the frequency gets higher.

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An electronic component is not an ideal device. Besides nominal resistance value, a resistor has stray inductance and capacitance. The stray capacitance and inductance are very small and has little effect in the circuitry.

For example, an air-core inductor and a wire-wound resistor may be similar in construction. But the inductance of the inductor is much larger than the inductance of the resistor while the resistance of the inductor is much less than the resistance of a resistor.