AES cartridges and MVS cartridges are made of two, dual layer boards. Chips facing upwards, the top PROG board holds the P ROMs (68k code) and V ROMs (sound samples), while the bottom CHA board holds the C ROMs (sprite tiles), S ROMs (fix tiles) and M1 ROM ROM (z80 code).
EPROM and JEIDA flash carts by SNK. Capacity ?
Prototypes cartridges with green labels are the more common Japanese versions.
Mahjong Minasan no Okagesamadesu prototype (picture by NeoGeoCollector):
Prototype cartridges with blue labels are the Export versions. These are extremely rare and only one cart with this label is known.
Viewpoint prototype (picture by NeoTurfMasta):
These are the sample carts made when the game is somewhat complete. But there are also development carts developers used to test each of their builds, with easily removable linear flash cards.
There are some boards with a standard MVS form factor. Maybe an AES variant exists ?
Standard-sized flash cart (picture by www.neogeofreak.com):
And there are also some way bigger flash carts! Dragon's Heaven aka. DarkSeed was found on this kind of development board.
X3002 dev board (picture by NeoTurfMasta):
There are also EPROM carts in the same format, like this other X3002 but with eproms (picture source unknown):
Older X0007 with full height connector, mfg. same as early boards (picture source unknown):
Speaking of EPROM carts, there are even more strange cartridges, PROG8AM and CHA8AM (picture source unknown):
Another 8AM dev board. Does this one host Shinryu Senki ? (picture by Billy Pitt):