I consider trading as a professional activity. It requires analysis, research and others knowledges. Gambling you just require luck. But yes, maybe there is a thin line between then. It depends on how you do trading.
yes that is a face, trading is really a professional activity while gambling can not be consider as professional activity, because gambling is banned in so many countries and is consider as illegal activity in so many religions.
to me i think there is only one factor common in them and that is the risk factory, otherwise trading is a profession and gambling is just a activity for making money and nothing else.