Please, can anyone tell me what is the difference Eclipse is depicting between (1) and (2) the attached image?
Tried googling, but couldn't find any proper source stating above :)
This feature was introduced in Eclipse 4.8 to indicate that a source folder contains test code.
See New and Noteworthy, the section "Test sources" describes it in more detail.
I'll quote the relevant part here:
Test source folders and dependencies are shown with a darker icon in the build path settings, the package explorer and other locations. This can be disabled in Preferences > Java > Appearance