"Atlantic Walls" concentrates more on the lyrical tracks from the source albums it covers. It also showcases most of the great guitar-led ballads, which were so much a feature that Zlatko Perica brought to the band throughout much the 10-year period covered here.
This disc manages to find lots of guitar music from the earlier albums too and it is interesting to here it all combined in one place like this. That said, I'm not convinced that the selection works particularly well in the order presented - especially around the middle of the disc, where it feels to be very much a mish-mash of pieces with little or no cohesion. The end of the disc presents some of the very best of the music from the period, though, and would be a delight to have if you don't already own the source discs.
Taken as a pair, then, "Atlantic Walls" and "Atlantic Bridges" would be a fine purchase for anyone not wanting to buy all of the original discs to get at the best. Of the two, "Atlantic Bridges" is probably the more satisfying collection, while "Atlantic Walls" has arguably some better tracks.