Reader is the free version (which is why there are a lot of things you can't do with it compared with Acrobat).
Thanks.
I was confused by "Open in Adobe Reader.... [It costs.]" which implies that it's not free.
I'm not aware that Acrobat has a shareware version. One pays up front for a given version (which then includes various updates).
I meant to say "commercial" but lost the word. (On the other hand, the difference between the two is often blurred.)