You can look at the book of Mark Sanuders and his colleagues, Fifth edition, 2009, for page 106. (attached). They discussed all these issues in details.

thanks a lot brother

The word ontology is derived from the Greek words ‘ontos’ which means being and ‘logos’ which means study. It tries to pin point things around us that actually exist. It is the study of the nature of being or becoming existence and their differences and similarities. It tries to answer questions that begin with ‘What’. The scope of ontology can be generalised from philosophy to other fields like medicine, information scienceor even advanced physics. Ontology helps us to understand questions like what is God, what is a disease, what happens after death .

This is one of the core branches of philosophy which deals with the aspect of procuring knowledge. It is more concerned with the natural sources and scope and limits of knowledge. Epistemology is also derived from the Greek word ‘episteme’ meaning knowledge and ‘logos’ means study. This branch of philosophy aims at discovering the true meaning of knowledge.

The branch is divided into two parts:

• Nature of knowledge: This tries to explain what is meant when a person says he knows about something or event or when he says he doesn’t know about a particular thing.
• Limits of knowledge: through this researchers try to define the scope of knowledge. They want to know if knowledge is limitless. Can we know everything or there are certain limitations to what we can know.

Ontology is the beeing of things. It means the beeing itself for example of matter and not how matter appears to human. So if you are talking about an ontological theory of xy you try to explain how xy is brought to be in the world independently from how it is perceived by us. Epistemology instead is something different. It means attempts made by human to gain knowledge about the world. As humans we have several senses to realise the world we live in and we have brain that is used to interprate stimuli in a specific way (the way is set by experiences we make as individuals during our lifetime). So the way we see the world as humans is not the state of beeing of this world. For example as humans we cannot see UV-waveleghts but they are in the world. That is why scientists - who are humans - try to find a way of gaining objective knowledge about the world that is independent of the human perception. Epistemology therefore is the theory of gaining objective knowledge. But the question is more if we - as humans - will be able at all to produce that kind of objectivity or if - as I assume - will be bound for ever on the evolutionary strings of human thinking about the world.

Thanks your clear and convincing answer