Flush Markers
also known as flat markers, grass markers, headstones (head of grave placement), footstones (foot of grave placement)
Bevel markers
Also known as pillow markers or hickey markers. They have slope on the top. Typically the front is 2 inches short than the back. So a 24x12x8 would be 8″ tall in the back, 6″ tall in the front.
Upright Monuments
Upright monuments have two pieces, a bottom base, and an upright tablet. There are many different shapes. Generally (but not always), one gravesite is 3 foot wide, two gravesites 6 foot wide.