The RAMPS 1.5 is a variation of the popular RAMPS boards that, like all other RAMPS boards, is plugged into an Arduino Mega for operation. The layout of the RAMPS 1.5 is virtually identical to that of the RAMPS 1.4. The only real difference between the two are the MOSFETs and the fuses.
IMPORTANT: It is important to note that UltiMachine, the original developer of the RAMPS boards, does not develop the RAMPS 1.5. It is designed and manufactured by BIQU/BIGTREETECH based on the original open-source RAMPS designs but they have not open-sourced the designs or released any official documentation to date which is in violation of the original RAMPS hardware license.
Also, the positions of the D1 and D2 diodes have been swapped from the positions in RAMPS 1.4, the D1 diode is now the diode closest to fuse F2.