Just noted, in passing: MO has something on the order of 8,000 employees, while PM has fully 77,000 (!) -- and with that their revenues are, very roughly, in the same ballpark.
Don't know the exact breakdown today, but this difference is largely due to PM's operations in Indonesia. The most popular cigarettes there are called "kreteks", which combine tobacco with cloves. Most have to be produced by hand, and not by machine. Therefore, PM employs a lot of low skill and low cost labor there to produce those.
There might be some similar local factors elsewhere, but when it comes to machine produced cigarettes like Marlboro or even HEETS, the equipment and amount of labor used would be similar to the US.