execution plan not the same in 2 boxes (same RBDMS and DB)

The execution plan could be affected by the box load/ or by the machine characteristics (nb CPUs...). ?
(As I noticed that sometime, we don't have the same execution plan
in our test and production environments : same RDBMS version and same volume for the database).

Anyone have more info about this behaviour ...

Thanks a lot ...

has one got up to date stats and the other not? Parallel settings the same?

could be a whole host of things

Stat was calculated and both boxes (parallel setting is the same).