Lets start with the simplest answer, the difference between the two is bitcoin has a unpredictable prices it can go up or down that's why it's good for investment because if the price go down you can buy it for a cheap price and then sell it once the price goes up, it's simply a buy and sell concept.
And the transaction rates are cheap, not like in banks and stuff bitcoin offers cheap transactions if you exchange it with other currency usually you get it with no deductions unlike going to a money changer.

The other good thing about it is it keeps you anonymous, it is secured, and it's fast it's easy, creating a virtual wallet is very easy
and it is accessible to everyone. Bitcoins are not owned buy the government or any single entity, which means you can't control it.

In terms of gambling I don't have any experience in those yet,