Hi, I am only new but this one caught my eye as I had a debate about it not too long ago. Essentially, spreadbetting and CFD's are betting and not investing. Think of it like this (or just look at the name in spreadbetting. There is a big hint there), investing occurs when you invest money in a business or asset class. Its real. It can be touched, its a part of something real. You buy a share in a business, you invest in that business. You put money on the chance that a stock price will go up or go down, but you dont actually invest in that company - this is betting. You may as well go to Paddy Power and ask him for odds.
Pretty plain and simple in my eyes.