Question

Difference between biased coin and unbiased coin

Answer 1

Biased coin will have both tail and head
But for unbiased coin both will be tail or both will be head

Answer 2

In unbiased coin both the sides have the same probability of showing up i.e, 1/2 =0.50 or 50% probability exactly when experimented with both sides alternately facing up before tossing the coin in air under identical conditions. 
In a biased coin probabilities are unequal. That is any one side has more than 50% probability of showing up and so the other side has lesser than 50%chances of turning up.