See in site // https://en.wikipedia.org/wiki/Liger or in

https://www.quora.com/Is-a-lion-and-tiger-one-species

There is no answer.

Here the question is why both different species if they can produce fertile offspring.

As per biological species concept the living being which can interbreed and produce fertile progeny considered species.

While here both are differ but they producing fertile offspring.

Good explanation of the problems with the biological species concept here: https://blogs.scientificamerican.com/evo-eco-lab/species-concepts/

there is no answer of this question.

this is good for knowing the biological species but the problem is remain same.

Both liger and tigon males are sterile

No both are fertile.

Yes it may be ,but I don’t think the resulting offspring is fertile .Because according to the definition of species concept ,it is a group of similar individuals that can mate with each other and produce fertile offspring and are reproductive isolation from other species, although there is no exact definition of the species, but this is the best definition of biological concept of the species ,but some times this isolation breaks down and mating occurs and the offspring is infertile and better an example is the mating of horses and donkeys and the production of mules.

Where did you read males are fertile?

Thanks for everyone.

But still the confusion remain same.

I think you should check your font about fertile males, then everything will became clear.