Its certain that both anime series events happening in a world of Magic and Magical power is essential in both animes. But is that what make both animes similar.

In order to fix this misunderstanding we must note the key difference between those two anime series. And here a list of differences between them:

Magic isn't everything

You may notice that in Black Clover everyone possess a magical power except Asta the main character in the story, however in Fairy Tail not all the world characters possess magical power or magical abilities

Spells Book

In Black Clover in order to be able to use a spells you're required to have it in your grimoire (Book of Magic Spells), instead in Fairy Tail there is no grimoire and people are able to use spells without using any grimoire

Training and Magic

Its clearly shown that in black clover your magical power or orientation/category is defined once you're born and you may born with a powerful magical power as we can see with Yuno and the noble families, that make less training is required as the noble families can perform a high or wide range magical power without even training. This is not the case in Fairy Tail where everyone possess the magical power by training and hard working. as an example everyone of the Dragon Slayers possess the power of the Dragon in charge even if they born without any sort of magic before the dragon training.

Story

Both animes have their own story, when in black clover two friends compete to become the next wizard king, In fairy tail we have a series of adventures in a story to save the world from villans and dangerous clans

Conclusion

Both animes have their own touch which make them both more enjoyable to watch