We've just renamed "Observations" to "Tasks", so don't get confused - nothing else changes. This label is more descriptive of what the system actually does.
"Projects" contain "tasks" and activated "tasks" can produce "observations" consisting of one or more images. Whenever a "task" is invoked again by the robotic scheduler, more "observations" are made for the project. Thus, you can re-use the same task over and over again to produce more or slightly different data. See the revised Help pages for more information.
That's all. Really quite simple. Or as we say in German: "Raider heißt jetzt Twix, sonst ändert sich nix!" ;-)