The distinction between direct and indirect object can be made on the basis of semantic and positional information:

Direct object

1. semantic role: it is usually directly affected by the action.
2. position: it is usually the second one if two objects occur.

Jesse James killed dozens of innocent people.

Our hosts gave us a warm welcome.

Indirect object

1. semantic role: it is usually an animate being that is the recipient of the action.
2. position: it is usually the first of two objects.

Our hosts gave us a warm welcome.