I was recently asked this question here is my two cents:
eLearning, CBT, WBT, mLearning, Online Learning all use a computerized devices to access content in some fashion.
As such they all have a common core, however differences can be found for each.
- eLearning – Traditional with SCORM Output would be LMS reliant to fully function
- CBT – Computer Based Training: Does not have to be online
- WBT – Web Based Training with a WWW networking requirement
- mLearning – Similar to eLearning but normally requiring access to a cell phone provided for data and requiring content be responsive to work on a mobile device
- Online Learning – Could be either eLearning, WBT, mLearning as it encompasses more than one method. Perhaps best known as being a catch all phrase for a variety of computerized training mechanisms.