LMS theme with front end specific user login

Hi all,
I’m researching LMS models for a company based e-learning portal. Am looking at WP, Joomla and Drupal as possible solutions.

The project is to set up a system that teaches and tests two different types of user.

User 1 (sales personnel) would get access to content A (simplified content)
User 2 (Engineers) would get access to content B (complex content)

This model therefore needs a user database to define the two different users, as well as a login screen that channels the right user to the right content.

Anyone know of a theme and/or plugin that allows differentiation of users to content?

cheers
Gavin