Acute back pain is usually done with certain activities, e.g squatting in the gym or picking up a box from the ground with poor technique.
Sub-acute is usually a dull ache that has been lingering around for a few weeks that can sometimes favour one side in particular, this can occur when taking on something new. It has happened a lot during the pandemic period as a lot of people have gone from an ergonomic office space to their dining room chairs and tables.
Chronic pain is usually a form of pain that lingers around for 3+months and is usually a result of misalignment throughout the body. The pain will usually be described as quite a nervy, tingling/burning type of pain.