33.8.3 Summary - Difference present and perfect participle
For a bit clearer view we present the given examples also as relative clauses, then you can see the difference in another light.
das schmelzende Eis => das Eis, das (gerade) schmilzt (the ice that is melting [right now])
Active (present) tense
die liebenden Männer => die Männer, die lieben (the men that love)
das geschmolzene Eis => das Eis, das geschmolzen ist. (the ice that is melted [already])
die geliebten Männer => die Männer, die geliebtwerden. (the men that are loved)
* see chapter 18 about the differenc passive voice forms
As you see it things always return even if you think that they are not really of importance as the difference between the passive voices. However, if you feel this is too much detail for a book on grammar, just forget all about it, you will do it right - we are sure!
Schlage die Trommel und fürchte dich nicht und küsse die Marketenderin, das ist die ganze Wissenschaft, das ist der Bücher tiefster Sinn.
= Hit the drum and do not fear and kiss the marketeer's girl, this is the whole science, this is the deepest meaning of books.