What is the difference between 20th century and 21st century skills?

Digital - 21st Century skills
 What is the difference between 20th century and 21st century skills?
My understanding of the differences and shifts in thinking are based on the changes in thinking about how students learn and how they are assessed.
20th century learning was assessed by using a range of tasks and assessments designed to check proficiency. Students were ranked with an assumption that not all will become proficient. A grading system ranked students in terms of academic accomplishments and their mastery of relevant skills and knowledge.
  The 21st century shift that has occurred places  greater emphasis on learning outcomes and the desire to help all students master the skills and competencies. The use of rubrics such as SOLO or Blooms Taxonomy show performance standards and clearly defined learning objectives in a way that students can articulate and evaluate performance standards.
  The 20th century model of teaching had the teacher as the main source of knowledge, and that knowledge was imparted to students in the same way as has been done for centuries. Students were expected to engage and learn by watching and listening to the teacher, then copying or reproducing that knowledge in a task.
 In the 21st century there is a much greater expectation for educators to be familiar with neuroscience and cognitive and developmental psychology. These will inform the teaching and the use of higher order thinking, metacognition and multiple delivery modes will be some of the tools required to reach students in a way they can engage.
  Confusion or gaps in understanding should become more apparent in the 21st century as a result of embedded assessments. These will help the educator understand how students learn successfully. This should also lead to personalised or individualised learning pathways tailored to students needs. The use of effective technology can enhance this process and allow the anywhere, anytime learning. The collaboration and connectivist nature will widen the learning experience beyond the classroom and into the world.
Real world tasks or problems and project based learning come to mind as catch phrases. I guess the shift will be in the ability to put these into practice in an effective learning environment where students drive the learning and can articulate not only what they are learning, but how they are learning and why.