The phrase "different calibre" means that something or someone is of a higher or lower quality or level compared to others. It suggests that they stand out in terms of their ability, skill, or importance. Full definition
If he wins the Europa League, with Champions League football he'd have an entirely different calibre of players available in the market. (justarsenal.com)
Ozil can not even turn creatively like Sane and Aguero, let alone have the same vision as Silva and Brune, but some people said he is of different calibre?! (justarsenal.com)