what advantages does one have over the other?

what are some situations where you would use one over the other?

I've seen many reviews comparing each to mono but non comparing them to each other.  Maybe you guys could help shed some light for me =D

Thanks!

Advantages of Flouro would be less visible under water and less stretch meaning a better feel of your bait.

The biggest disadvantage I've noticed of Flouro is knot strength.  I believe someone posted some graphs from tests they did on the 2 types of lines and Flouro's big disadvantage was in knot strength.  I experience more break offs with Flouro over copoly and they always happen right at the knot.  

To me, the biggest difference is that Fluoro will sink and Copoly floats.  Thus Copoly is good for Topwaters and Fluoro is bad.  But Fluoro helps cranks/jerkbaits get deeper than they will with Copoly.

While the less visble and less stretch may apply, I don't really notice that much difference between the two in that area, but I do as far as the sinking versus floating.

Fluoro is also much more sensative!

Fluoro has a lot less stretch than copoly but knots wont hold up after a few fish. knots arent a probelm if you retie every time from my expreiance and i use fluoro religously. fluoro is not good if you dont like retying alot