허리 - 등
허리 means waist and back, but in case it means 'back', so any difference with 등. For ex, I have a backache

'허리가아빠요', 아니면 '등이 아빠요'.

Question

허리 - 등
허리 means  waist  and back, but in case it means 'back', so any difference with 등. For ex, I have a backache

'허리가아빠요', 아니면 '등이 아빠요'.

Answer

허리 means "the part of a body between rib and buttocks" which is waist and the lower part of back.
등 means "the opposite side of chest and abdomen" which is the upper part of back.
등허리 means "the lower part of back"

"I have a backache." can be mean 
등이 아파요. (upper back pain)
or 
(등)허리가 아파요. (lower back pain)