they actually aren't the same thing, in a beta, you test an unfinished game and give feedback about the bugs and glitches, most of the time its limited to just a couple of hundred persons, in the other hand, a beta is just a small portion of the final game, its open to anybody most of the time, just like this demo, It'll be available next week for anyone, though rumors say that the demo will have a limit of 30 plays before becoming un-playable.
about trading it or not, I'd say that's all about the person, I didn't get a code but I was lucky enought to get one for free from a kindy cag
In this case I feel like you are just a little butthurt that you didn't get codes to trade, that's why you are arguing about people trading them, I can certainly say that if you had gotten an email you'd have traded yours, I know what it feels like, I've faced it too, don't wanna start a fight so just lets say, may everyone do whatever they want with their code.