Don's given you enough information to tell the difference between a tenor banjo and a plectrum banjo. If it's a plectrum banjo, it is traditionaly tuned CGBD (low to high), and if a tenor, it's tuned CGBD. This is the tuning used for jazz, but modern Irish players use EDAE because it gives the same fingering as a fiddle (but an octave down).

Hope this is useful
Ray