wave is all about starting from a clean slate -- not constrained to integrate with existing systems. buzz is all about leveraging gmail by adding broadcast and location.
If buzz were a good product it would stand on its own merit without needing to "leverage" gmail. The trouble is that it's not a good product -- it's a lame me-too effort that offers little over its rivals (Twitter and Facebook). Me-too is fine so long as you bring something to the table, and buzz doesn't seem to, except for gmail integration, which an awful lot of people think is actually a hindrance.
Google have shown time and time again that they don't get "social networking", which is fine because they're a search and ads company and they do get those[1]. (I'm thinking of Orkut, OpenSocial, the way they introduced following into Reader and now buzz).
[1] the recent facebook login debacle aside
Oh, and the (pretty much separate) geolocating public Buzz layer on Maps for mobiles is very nice. I discovered a tea place I want to check out just round the corner from my house, if nothing else.
It is expected that even the Google designers themselves could not predict how or where their systems could be used.
But now it is clear: Google Buzz is social media, competing in the same space as Facebook and Twitter. Google wave is enterprise colaboration, competing in the same space as Exchange/Outlook/Sharepoint.