According to a source I found on the net, they're just different
names for the same thing.
"Many of the different colors of tourmaline have a name that may be
used when the gem is offered for sale. The red colors are called
Rubellite, blues are Indicolite. Other names less often heard are
Verdite for green, Dravite for browns, Achroite for the rare
colorless Tourmalines and Schorl for black tourmaline. The
multicolor stones can be referred to as bi-color, tri-color or
watermelon (picture a green rind and red center). A strong green
Tourmaline, found in east Africa, that is colored by the trace
element Chromium has found a small but loyal following, probably
because its color duplicates that of Tsavorite garnet. Paraiba
Tourmaline is a rare variety of blue to green tourmaline that is
found only in one location it the world--the mountains near the
village of Paraiba in Brazil. It is unique in that it is the only
Tourmaline whose color is derived from the trace element copper.
This variety of Tourmaline can occur in truly neon hues, which
command much higher prices."
Charleen Tyson Weigel