OK, so you mean the A Pillar PLASTIC TRIM?? That's a *totally different* question. The A Pillar is the windshield frame/support structure, not the trim.
The A Pillar in a convertible is most certainly different. I suspect the trim is also different, but I guess it's remotely possible that it might be the same.
If you go to
http://REALOEM.COM/BMW you can look at the online parts catalog for each model, and in theory compare the part numbers between the two cars to figure it out.