difference between logistic regression and binary logistic regression
binary:logistic is used for binary classification where the target variable takes binary output [0, 1]

reg:logistic is used for regression where the target variable is continuous between [0, 1] 

Quote from xgboost doc:

We use linear regression here, if we want use objective = reg:logistic logistic regression, the label needed to be pre-scaled into [0,1] 

https://github.com/dmlc/xgboost/tree/master/demo/regression