Multi angle you can see as 2 (or more) video tracks interleaved. As you can have more audio tracks you can have more video tracks. The multi angle tracks MUST have the same GOP structure.
(Seamless) branching is branching between different parts of video. If you want to skip a scene for instance you can use this. But to make it seamless is a bit more difficult and I don't know how to do it. With dvd-lab pro you have a branching option but it isn't seamless, there's a small pause at the bracnh point.
Editdroid crawl is multi angle. Don't know what program was used to create it. But with dvd-lab pro 2 you can also make multi angle titles.
Edit: The reason I want to create seamless branch titles is to make 1 dvd that has both the normal version of a film and for instance a version with deleted scenes reinstated.