Multicam and OCP are often used interchangeably, even in military regs, but there are differences. Multicam has more brown and cream colored blotches, as well as more vertically oriented elements.

OCP looks less "busy" removing the vertical elements and the brown and cream blotches tend to be larger. OCP also has deeper shades of green and brown. This was probably intentional so it stayed effective over time as it fades from sunlight and wear. At some point used OCP will have very similar colors as new Multicam.