Share dealing is where you actually buy and own shares in a company. You buy them and hope they increase in price to sell for a profit at some point in the future. Some shares will also pay you dividends, sort of a profit share from successful companies. There are many strategies etc. and a good source for this is www.fool.co.uk. You can only gain money if the shares increase in value.
With spreadbetting you can gain money when the share goes up or down. With spread betting you take an opinion on the movement of a share and gain or lose per point. Example: I think Tesco are in a good position and their share price will increase and I will bet £2 per point. If Tesco shares rise by 10 points, you get £20. Conversely if they go down by 10 points, you must pay £20 to the spread betting company. Its a little more complex than that as the company offers slightly worse rates than the actual share price in order to make money.
With spread betting please remember you can have an infinite loss. If you bet that a company will go down something could happen and the price rises and rises. Theoretically there is no limit to the rise and you will pay per point, so the losses could be unlimited.
I don't know too much about the other share and investment vehicles other than ISAs and savings accounts.
Hope some of this was of interest.
Joe Blogs