Peaceful mode is a difficulty setting, one which allows you to mine, build and explore without fear of attack, but without the limitless resources of Creative mode. Hostile mobs will spawn, but will be removed instantly so you will never see them. Switching to creative mode will also remove all hostile mobs, apart from enraged wolves, and tiny slimes.
In peaceful mode, you can't eat, but your hunger bar never depletes. Also you will regain health over time, even if you are hungry (ie, in the case that you switched to peaceful mode after your hunger bar went down in a different difficulty setting). You can still be killed, if you take damage too quickly.
Chat with our AI personalities
Yes
Yes it does.
There are only non-aggressive mobs when you are on peaceful.
If the difficulty isn't set to peaceful, mobs will spawn in creative mode.
You may have your difficulty set to Peaceful. Monsters will not spawn in Peaceful mode.