There is equal contribution, core contribution, and then the order of authors. Which of those attributes have actually which meaning? I thought the order defin

There is equal contribution, core contribution, and then the order of authors. Which of those attributes have actually which meaning? I thought the order defines how much someone has contributed. Core contribution sounds like it should be the most, so it should be first but it is not here. Equal contribution sounds like it should come right behind each other in the order but this is also not the case here.