They both have very similar methods, is one of them safer than the other, What is the real difference?
According to the unofficial docs below, it sounds like MemoryFSHandler is a type or subclass of FileSystem, which is probably why they have similar methods. The memory one just stores the data in a stream in memory though whereas FileSystem is just a file opener, much like Python's own "open" method. Personally, I've never seen either used in practice, although upon Googling for info, I found out that wx.HtmlWindow uses both of them internally. I always use Python's I/O libraries though.