I can't spot the differences between 4'x8' blackFoot and the 4'x8' greenBull (except for laser head option): please, can you tell me?

Only our greenBull CNC machines will be able to use the long Z-axis, due to structural construction of the greenBull over the blackFoot. The height from the table top to the bottom of the gantry is: 4.25" Both the maximum cutting height and diameter, will be dependent on the specific end mill/router bit you plan on using, since they can vary in length. The maximum cutting height (useful to engrave or cut material)is: with spoil-board 3.875", without a spoil-board is 4.625" The maximum diameter will (estimated) is: 3" Specifically dealing with our greenBull long Z-axis CNC machines, depending on how you specifically design the table you can have more cutting height and a larger diameter clearance. If you only create a frame for the machine with a hollow center(adjustable midsection), allowing you to have a greater clearance. Similar table image here: (https://buildyourcnc.com/Item/cnc-machine-greenBull-v4-6X#prettyPhoto/5/)