R is a language and environment for statistical computing and graphics. R can be considered as a different implementation of S. There are some important differences, but much code written for S runs unaltered under R.
SAS provides tools for mastering data access, management, analysis, and presentation. SAS provides a scalable, integrated software environment specially designed for data access, transformation and reporting. It includes a fourth-generation programming language; ready-to-use programs for data manipulation, information storage and retrieval, descriptive statistics and report writing; and a powerful macro facility that reduces programming time and maintenance headaches.