If they're both PF corrected, then the power consumed would be about the same.
The advantages of an electronics ballast are weight reduction and a wider input voltage range. It's also possible to do dimming/power reduction to the lamp if so desired. Of course, the disadvantage to an electronic ballast is that it's much more complex and not as robust as a mag ballast.
Greetings from Austin,TX
Former R&D Manager/Designer
High End Systems (Automated Lighting Manufacturer)