Difference between problem ticket and major incident

Answer:
Problem ticket is a record where all details about particular problem are recorded. Problem has task to find out a root cause of one or more incidents (what caused them). On the other side, major incident is an incident (malfunction or unavailability of a service) with higher impact and urgency. Meaning, once the major incident is resolved - a problem will be opened in order to find root cause and prevent future incidents (of that kind) to occur.
Learn more about this here:
"ITIL and ISO 20000 Problem Management – Organizing for problem resolution" https://advisera.com/20000academy/blog/2014/07/29/itil-iso-20000-problem-management-organizing-problem-resolution/
"ITIL Problem Management: getting rid of problems" https://advisera.com/20000academy/blog/2013/08/05/itil-problem-management-getting-rid-problems/
"Major Incident Management – when the going gets tough…" https://advisera.com/20000academy/knowledgebase/major-incident-management-going-gets-tough/