Marker & Markerless
AR with marker
With marker based AR you'll need a "marker image", which could be any printed photo, image, business card etc. When you'll frame that image with your camera, the AR content will be activated and will "follow" the image in the real world, like it's attached to it.
With Markerless AR, you don't need any marker, your AR content will be PLACED on top of a flat surface in the surrounding space, you'll be asked to scan the nearby environment to find a suitable surface.