They are both mound builders.
The crops they grew were maize, barley, sunflower, squash, goosefoot, may grass, and wheat.
They have several documented and still-existing earthworks that are around today, in Ohio and in nearby states. The most famous earthwork was the Serpent Mound in Ohio. For pictures and information...
They have nothing in common.
the mississippians are mound builders and they are the last of the mound builders in the usa