for every rows garden puzzle, there are five files sent out:
1. the regular version of the puzzle as a PDF
2. the thorny version of the puzzle as a PDF
3. the regular version of the puzzle as a .jpz
4. the .rgz version of the file
5. the solution as a PDF
the PDFs are self-explanatory—you print one out and solve it on paper. (or if you have some kind of useful software that lets you write on PDFs, you could do that, too.)
the .jpz file can be used to solve on a computer using one of two apps that i know of: the in-browser crossword nexus solver, which works with any modern browser, and a stand-alone free app called XWord, available for mac or windows. in either case, you'll need to save the .jpz file to your computer somewhere and then locate it to load in the app. due to limitations of the .jpz format, only the regular version of the rows garden is supported; basically, you can't have clues that are associated with entries whose grid locations are unknown.
the .rgz file is for use with robert bosch's rows garden mobile app, available for a few bucks on iOS and android. the file itself is not specific to the regular or thorny version; rather, you can customize the settings within the app to mimic either of those versions—or something else to your liking. if you want to duplicate the presentation of the thorny version, set the bloom clue order to alphabetical by clue; if you want the regular version, set the bloom clue order to garden order; for both of those versions, set clue tag notations (things like "hyph." and "2 wds.") to on. however, there's no rule that says you have to set your settings to one of those! if you want no notations, or if you want full enumerations, or if you want bloom clues ordered alphabetically by answer, those are available as options within the app.
(note: the XWord desktop app can also read .rgz files, but it does not have any of those options. you'd be solving what amounts to a regular version, but without clue notations.)
for variety puzzles, sometimes there are only PDF options, and sometimes there's also a .jpz file. it depends on the puzzle type; in general, i try to offer a .jpz when the puzzle format allows for it. again, for .jpz files, i recommend either the crossword nexus solver or XWord.