Actually christmas, easter, and thanksgiving cacti are three different species (not just two).
If you want a true christmas cactus, look for leaves with a more rounded look. If they have points, you're probably looking at a thanksgiving cactus.
Either way, they're all great plants, they just have slightly different flowers, and different flowering times. You probably wouldn't notice the difference though.
I say get'em just cause they're nice plants, but keep them out of the bird's access.
Not sure about aloe, but the yellowish sap just underneath the surface of the leaf is an irritant and can cause nausea, etc.