FT8 versus WSPR

Both these modes are part of the WSJT-X suite from Joe Taylor. 

WSPR needs about 6Hz of spectrum (not much) and 2 minutes for the most common form of WSPR.  WSPR is really a beaconing mode.  

FT8 is a communications mode and needs about 50Hz with 15 second TX slots. WSPR works with signals much weaker than FT8. FT8 works with signals much weaker than SSB or CW.

Both offer the minimum exchange of data and neither are "chatting" modes. As they work with very weak signals and need so little bandwidth they have been transformative in amateur radio. They are not instead of speech modes, but as well as.

There are other modes also available in the free WSJT-X suite.

Personally, I enjoy both modes, especially as my voice is poor since my 2013 stroke.