Theory:

Let's see a situation before we get into the Unlike fraction.
 
At a birthday party, everyone dressed in different colors of costumes. Which made the birthday party so colorful. Here the different people wore different colors.
 
Similar to the above event, unlike fractions are fractions with different denominators.
Unlike fractions are fractions with different denominators.
Example:
45,23,67,2410,4515
 
Here the denominators of all the fractions are different, hence it is a, Unlike fractions.