They are not the same.
You don't need to do this,
List<Int_No__c > outField = new List<Int_No__c >([select Id,Name, from Int_No__c where Dir__c ='Out']);// consumes more cpu power
You should always use the below method with a query.
List<Int_No__c > outField = [select Id,Name, from Int_No__c where Int_No__c ='Out'];
The constructor of the List class
List<T>(listToCopy) creates a new instance of the List class by
copying the elements from the specified list. T is the data type of
the elements in both lists and can be any data type.
IF you want to copy some list to new instance then you can use like below
List<Integer> ls1 = new List<Integer>();
// Create a list based on an existing one
List<Integer> ls2 = new List<Integer>(ls1);
// ls2 elements are copied from ls1
System.debug(ls2);// DEBUG|(1, 2)