Weak or Narrow AI
These are non-sentient machine intelligence focused on narrow paths and work goals. At most, majority of the existing systems considered as Artificial Intelligence are actually weak AI. Example: Siri, Cortana, Alexa, are all narrow or weak AI. Siri and Cortana both operates within a restricted pre-defined range. There is no self-awareness, no life and no genuine intelligence of its own. Weak AI, does not attempt to perform any full range of human cognitive and neuro abilities.
Artificial General Intelligence (AGI) or Strong AI
A machine which can perform strong intelligent tasks and actions just like humans is known to have Artificial General Intelligence or Strong AI. AGI can basically perform tasks like reasoning, solving puzzles, making judgments, planning, learning, communicating in natural language and integrating skills towards common goals just as humans do. AGI also has the ability to sense, act and behave in a certain way. There are computer based systems now which do exhibit many of the above mentioned capabilities. Example: Decision Support Systems, Robots, Intelligent Agents etc.
The intelligence surpassing far from what the human brain can imagine, think and grasp is referred to as super intelligence. Philosopher Nick Bostrom of University of Oxford defines Superintelligence as “an intellect that is much smarter than the best human brains in practically every field, including scientific creativity, general wisdom and social skills”. Only time will decide whether humans will use superintelligence to modify their cognizance or thinking capabilities or whether superintelligence will constantly be updates and will lack the limitation human cognition has.