Most sources on the internet, such as How are 化け物, 妖怪, 幽霊, etc. related to each other?, seem to say that 化け物 and おばけ are two separate words for the same type of creature. But even if that's true in theory, in practice it seems better to understand 化け物 as 'monster' and おばけ as 'ghost'.
It would seem kind of silly to call a person おばけ as an insult, for example. The Google results for searching 化け物 are things I would recognize as monsters but not as ghosts, and おばけ gets ghosts rather than monsters. Same goes for ばけもの and お化け (though the results for お化け are rather creepier than おばけ).
So: In practice, is there a difference between 化け物 and おばけ?