DS1 is about to go into Y10, and tells me he is doing BTEC, rather than GCSE PE.
His school split the year into two haves for PE, and DS is at the top end of the lower half. The top half are now going on to do GCSE PE, and the bottom half are doing BTEC.
DS says there is more writing and less actual moving involved in the BTEC than the GCSE, which is why the less sporty people do it. 
What is the real difference?