We’ve already touched on one of the downsides of offline work. In order to find offline work, you’ll be limited to searching in your immediate area. (After all, you can’t take an in-person part-time job in Finland if you live in Iowa.)
On the other hand, you can take a remote job anywhere, as long as you can speak the language and have the necessary skills.
Online work has a few other advantages. It’s typically highly mobile, insofar as you can often do it from anywhere you can set up a small office. The hours are often flexible. Finally, it often pairs well with a full-time, offline job.