I can see why this question was asked, since they do have some similarities.
The villains attacking Roxy, which is similar to the villains constantly attacking Bloom.
That and Roxy, in a way, is one of the main focuses of season 4 (if not the main), like Bloom was for the last 3 seasons.
Though, there are many differences as well (personality differences). The characters are not the same by any stretch of the imagination, if you ask me.
Although, here's my thought about Roxy being Bloom's "replacement":
Since Bloom's plot is done and over with, they needed a different plot, (thus where Roxy comes in, which, one could argue, is essentially taking the place of the spot Bloom used to fill.)
Though, that's only what I can gather from the season so far. We haven't seen all of it yet, so the grounds of judgement in this case are a bit unsteady.
QUOTE (Bloomrocks1234 @ Jun 19 2009, 10:06 PM)
some people say that roxy is stronger but i say they are about the same when roxy master her powers now bloom is more powerful but after when roxy master her power everyone i think are the same equal power no one is stronger then the other because believix is also about people believing in fairies
I don't think Roxy is stronger then Bloom. Haven't we been told at the very beginning of the entire series that the dragon fire created the "magical dimension"? I doubt that Roxy would have a power that is stronger than that, but again, we've only seen half of the season so far (and you know how Winx is sometimes: anything goes).
I, personally, wouldn't even rank her powers/abilities among the other characters yet because of that fact. I don't think we know whether she's stronger then this character or that character quite yet.