axes configuration on extruder and bed plate

hello ... i'm a master student and i'm working on my thesis about FDM 3d printers. i want to know about following question. "what is differences between axes placement arrangement on extruder and bed plate?" (z head-xy bed),(xy head-z bed),(xz head-ybed),(xyz head),(x head,yz bed) ...
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it's just a question that i have about project ... the detail topic of my thesis is "Design and optimization of support in additive manufacturing process based on polymer extrusion" before i do my thesis i must manufacture a fdm 3d printer ... It should be noted that we are three people ;)