$+18 > 890D 38E83B06 MOV DWORD PTR DS:[63BE838],ECX
The instruction MOV DWORD PTR DS:[63BE838],ECX
starts at +18h from your start point, but the address itself that is hardcoded in the instruction starts 2 bytes later:
890D 38E83B06
38E83B06
in reverse byte order: 063be838
. Ollydbg seperates this visually nice for you.
When trying to get the offset of a constant in an instruction you have to look at the bytecode (second row in ollydbg). You will find your constant embedded there and have to take the offset from the beginning of the instruction.