Gini coefficient vs Gini impurity - decision trees
No, despite their names they are not equivalent or even that similar. 


Gini impurity is a measure of misclassification, which applies in a multiclass classifier context. 
Gini coefficient applies to binary classification and requires a classifier that can in some way rank examples according to the likelihood of being in a positive class. 


Both could be applied in some cases, but they are different measures for different things. Impurity is what is commonly used in decision trees.