There are ways in which you can make that distinction objective to a certain degree. For example, by looking at responses that could be generated in the brain to exactly the same stimulus and there could be differences there.

There's something that intervenes and is very important which has to do with value. Value in the true biological sense, which is that contrary to what many people seem to think, taking it at face value - sorry for the pun - we do not give the same amount of emotional significance to every event.

When we talk about emotion, we really talk about a collection of behaviors that are produced by the brain. You can look at a person in the throes of an emotion and observe changes in the face, in the body posture, in the coloration of the skin and so on.

You can be highly concentrated on a person, on a problem, and be so good at excluding all other material that that becomes not just the focus of your experience, but practically the sole content of your experience, everything else falling by the wayside.

Something may have happened before, and yet this thing that happened just after may be so important that you don't even know about the thing that happened before and when you tell your story to yourself, or to someone else, it's going to be told not on the basis necessarily of the time course, but rather on the basis of how it was valued by you.

Emotions are enmeshed in the neural networks of reason.

Consciousness, much like our feelings, is based on a representation of the body and how it changes when reacting to certain stimuli. Self-image would be unthinkable without this representation.