The two languages - PBASIC and Arduino history 

PBASIC is a version of the BASIC Computer Language (Beginner's All-purpose Symbolic Instruction Code)

PBASIC was created by Parallax, Inc. 

It is a "modern" or "structured" BASIC.

PBASIC on Wikipedia - http://en.wikipedia.org/wiki/PBASIC

BASIC on Wikipedia - http://en.wikipedia.org/wiki/BASIC_programming_language

The Arduino language is based on the Wiring language, and is implemented in the C programing language.

Arduino Extended Language Reference - http://www.arduino.cc/en/Reference/Extended

Arduino on Wikipedia - http://en.wikipedia.org/wiki/Arduino

Wiring language - http://wiring.org.co/

C on Wikipedia - http://en.wikipedia.org/wiki/C_(programming_language)