Target-Definition: Installation vs. Directory

Question

When i click add in the target-editor i can choose between:

• Directory (just plug-ins on the filesystem)
• Installation (only plug-ins, too?)
• Features (one or more from the filesystem)
• and Software Site (e.g. p2-repository)

So what's the difference between a installation (such as eclipse-SDK) and a directory, when the installation just fetch the plugins? I thought a installation would resolve my features, too. But it seems there is another difference, so what's the benefit?

Edit: Note if you want to use features with the type "installation", it's necessary to unjar the features.

Answer 1

An Eclipse installation contains metadata as to what was installed via Help -> Install New Software and other similar means. Since the installation process verifies dependencies, you know that your target platform is valid and will run. Defining target via an install will use the install's metadata to populate the target. Note that Eclipse has not been automatically detecting plugins copied into the plugins directory for several years now.

If you define a target by pointing at a folder that you put together by copying plugins, you do not know if the dependencies of those plugins are satisfied, so your target may not run.