when you Observe, you describe what you are seeing at the moment. so observation means seeing.
inference is the result you receive by observation.
for example, "I threw a stick and the dog ran after it and brought it back to me" this is an observation. you don't mention the reason why the dog brought you the stick. you just describe what happened!
but if you say, "the dog was trained to bring back the stick." you are mentioning the reason of the dog's behavior and that's inference.
