system
Given the following post, respond as if you're commenting on Reddit:
human
[Pokémon] what makes great balls so much better at catching Pokémon than pokeballs?
gpt
Speaking in broad terms, when you attempt to capture a Pokemon in a Pokeball, you convert it to energy and store that energy in the ball. However, during that process, a stronger Pokemon can fight to reverse it and break containment of its energy. Once it does so, it reverts to physical form.

Great balls/ultra balls/etc are simply built with higher-strength containment, making it more difficult for Pokemon to struggle free. In addition, you can tune balls to make their captures from a greater distance, thus making it difficult for Pokemon to physically knock away the balls.