This paper is an analysis of two knowledge representation extensions of logic programming, namely Answer Set Programming and ID-Logic. Our aim is to compare both logics on the level of declarative reading, practical methodology and formal semantics. At the level of methodology, we put forward the thesis that in many (but not all) existing applications of ASP, an ASP program is used to encode definitions and assertions, similar as in ID-Logic. We illustrate this thesis with an example and present a formal result that supports it, namely an equivalence preserving translation from a class of ID-Logic theories into ASP. This translation can be exploited also to use the current efficient ASP solvers to reason on ID-Logic theories and it has been used to implement a model generator for ID-Logic.