In short
Dr Jekyl was a Benevolent(good hearted), intelligent, well thought person. He was looking for cures and answers(the good in life).
Mr. Hyde on the other hand was a malevolent, malicious person, who only thought of himself.
In otherwords, you're being called two faced. In one instant you may seem to be a world class person. But in a moments notice, you seem to change into a totally different persona. All of a sudden its like it went from a sunny day with no clouds, to a miserable downpour with no sun to be found. You become self centered and unaware or seemingly careless of others feelings.