Specifically, Collaboration diagrams are better for showing the dynamic structure of the system (which object collaborates with which others), whereas sequence diagrams concentrate on the timing aspect (which message gets send when). Many UML tools are able to automatically convert one into the other.
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus