Probably the biggest difference is that you can not play traditional gambling in many places. Many countries do not allow casinos to be opened and all you usually have is sports betting in many countries and some do not even have that. So people go back to online gambling.

However even if I was living in las vegas out of all places, I would still sometimes gamble at home because it is just easier to open up your pc and gamble. The good part of online is the ease of gambling whenever you want in any state you want. I can gamble while eating and watching a show as well. Traditional is still more entertaining tho.