In this particular game type you have no limit to your things & the cubes you use can be mined super quickly. You are also able to fly & can not die. This game type is specifically for those people who just want to invent super cool things like furniture or homes.
Here are some things that you are able to alter in the map options:
How the environment affects you
The Time of day
Varying Climates effects
Places where you respawn
Being invincible: You are practically safe from everything. You wont die from falls & you regenerate at a very fast pace. Digging & mining go way quicker as well.
Challenging is the "normal" survival game type. There is danger, but you will be able to respawn at your last sleep position when you die.