Level 3 is equivalent to a school A Level and it teaches you to give a routine massage treatment for sport, relaxation, beauty or similar.
Level 4 is equivalent to a school a Higher National Certificate or university entry standard and this teaches some more advanced technique which can help in the recovery of common injuries.
Level 5 is equivalent to a Higher National Diploma or a Foundation Degree and at this level will you learn how to assess, treat and rehabilitate a wide range of injuries.
All awarding bodies (BTEC, ITEC, VTCT, etc) have to use the same criteria when approving qualification Levels and so they must all be equivalent to each other.
Some training providers offer a pathway up through the grades but this means you learn anatomy and massage at a very basic L3 which is not sufficiently for the clinical skills needed at L5. An integrated Level 5 qualification teaches the foundation subjects at the right clinical level needed for the advanced training to follow.