Top one is alluminium, the lower one is cast. The alluminium one is slightly different in shape (see the fins), they are also much lighter, the brake pads used are also different to the cast callipers.
As i stated before the parts you need will probably be the same on either of the cars you stated with rear discs.
Look at my picture to determine which ones you fitted as i can't tell due to the angle of the pictures in your previous post.
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Fiat Marea Chrome Front Grille. Fiat Bravo MK2 Front Grille.
ePER V4.0 2008 DVD, Bravo & Marea Workshop Manuals, Fiat Bravo Haynes Manual &, Fiat Bravo Owners Manual on CD etc...