The two are similar in origin and somewhat in style but divergent in size, complexity and maturity.
Both took the view that they wanted to implement a character-mode terminal-based line-drawing API modelled conceptually after AWT and/or Swing. Both use the Java Native Interface (JNI).
Charva describes itself as follows: CHARVA is a Java Swing-like framework for presenting a "graphical" user interface, composed of elements such as windows, dialogs, menus, textfields and buttons, on a traditional character-cell ASCII terminal. Charva's latest release took place in Sept. 2006.
JCurses describes itself as follows: The Java Curses Library (JCurses) is library for developing text terminal based applications using Java programming language. It is implemented as a Windowing toolkit similar to AWT, but built upon the UNIX "curses" windowing system. JCurses latest release took place in November, 2002.
JavaCurses is simpler, but it also needs some work. Charva is more solid, more modern, more complete, and performs better.
I'm coding on JCurses right now! It is cute and it needs me much more than Charva does.