How do I tell the difference between these two?

Some years ago I planted one or the other on the fence by the alley. They are gorgeous. I recently removed a shrub back there, and now there is an open spot that could use another clematis. I'd like it to match the ones already back there, but I no longer know which Jackmani type I planted there. Any identifying features that would help me get the right one?

If there is no major difference in appearance, I can easily locate a Jackmani Superba at my corner garden center. I have never seen the two together, so don't know if there is a noticeable difference to the casual glance.

Thanks.

Kate