I know that polarized having the + and - pins provided; non-polarized having flexible with pins connection. I am keen to know about the construction inside, which makes the capacitors differing from the polarized and non-polarized.
Kindly help me by answering or direct me to clear the doubt
There are several types of capacitors. And some are only polarised, others are available in both versions.
Ceramic caps are non-polarised. Just plates and a dielectrium in between.
Air caps and trimmers are non polarised in the sense that they do not break if connected the wrong way but functional they are often polarised (so trimming them does not add capacitance or is a danger for the user, you make the rotor the most grounded side)
Tantalum caps are always polarised. They blow if you connect them the wrong way
Electrolityc caps are made in both versions. The polarised one behave as a diode. The forward voltyage is about 1,5V. And when you go over that it will blow up after severe DC leakage. You can see a bipolar cap as just two caps back to back in series.
Some film caps and things like polystyrene caps are polarised. But you can use them safe the wrong way. This polarisation is to tell you what is the outside of the cap. This to minimise paracitic capacitance towards the ground plane.