Beware that Bitstream's version of Univers (Zurich) is drawn just a tad differently from the version of Univers in Adobe's type library. Other slight differences occur in Bitstream's version of other font families, check Square 721 versus Eurostile somtime.
That might matter if you have to match something exactly, such as replacing faces on a channel letter sign. The situation is more of a problem when dealing with various flavors of Helvetica and other clones of it. Standard Helvetica, Helvetica Neue, Bitstream's Swiss 721 and URW's Nimbus Sans all look very similar but are drawn just a little differently from each other.