although: sebbene, benché, quantunque, nonostante (che), malgrado (che)
even if: anche se, quantunque, seppure, con tutto che
Concessive conjunction requires always the congiuntivo in Italian. However we can distinguish four different situations. The action / events can have happened in the past or can happen in the present, the actions / events described in the consecutive clause be start at a certain moment or be achieved.
presence
The concessive clause describes the beginning of an action:
Benché lo dica, non gli credo. => Althought he says it, I don' t believe him.
The concessive clause describes the end of an action :
Benche l' abbia detto, non gli credo. => Although he said it, I don' t believe him.
past
The concessive clause describes the beginning of an action:
Benché lo dicesse, non gli credetti. => Although he said it, I don't believed him.
The concessive clause describes the end of an action:
Benché l' avesse detto, non gli credetti. => Although he said it, I didn't believe him.