Impedance and resistance are both seen as measure of the opposition to the flow of current...I. Just need a further explanation on differences between both

 

In general terms, yes. But there is a "Phase" factor too.
In a "Resistor", Both the Voltage and Current are in Phase, in an "Impedence" (applys to AC only), they need not be.
In a Normal Inductor, the Current Lags the Voltage by 90 degrees, in a Capacitor, the Current Leads the Voltage by 90 degrees.
In an "Impedence", the Current can Lead or lag the Voltage anywhere from 0 degrees to 90 degrees.

https://www.quora.com/Whats-the-difference-between-resistance-and-impedance
http://www.physlink.com/education/askexperts/ae517.cfm

 

Impedance and resistance are both seen as measure of the opposition to the flow of current...I. Just need a further explanation on differences between both

The key difference is impedance is frequency dependent while resistance is not.

In a purely resistive element, the current is in phase with the voltage and is independent of frequency. That is, the resistance is the same for DC and AC voltages.

In a reactive element, the current and voltage are not in phase and the current is dependent on frequency.
For an inductor, the impedance is jωL. For a capacitor, the impedance is 1/(jωC) where ω = 2πf and operator j introduces a 90° phase shift between the voltage and current.