Collecting is a hobby often involving the targeted search and acquisition of specific items that form—at least from the perspective of the collector—a greater appreciation, deeper understanding, or increased synergistic value when combined with other similar items. Hoarding, by contrast, typically appears haphazard and involves the overall acquiring of common items that would not be especially meaningful to the person who is gathering such items in large quantities. People who hoard commonly keep items that hold little to no true meaning or value to most others, unlike some collectors, whose items may be of great value to select people. Most hoarders are disorganized, and their living areas are crowded and in disarray. Most collectors can afford to store their items systematically or to have enough room to display their collections. Age, mental state, or finances have caused some collectors to fall into a hoarding state. Clutter Image Rating
A UK charity called HoardingUK, has found that people have very different ideas about what it means to have a cluttered home. For some, a small pile of things in the corner of an otherwise well-ordered room constitutes serious clutter. For others, only when the narrow pathways make it hard to get through a room does the clutter register. To ensure an accurate sense of a clutter problem, they created the Clutter Image Rating, a series of pictures of rooms in various stages of clutter – from completely clutter-free to very severely cluttered designed to encourage people to get support.
Compulsive hoarding, also known as hoarding disorder, Plyushkins disorder, is a mental disorder characterised by accumulation of possessions due to excessive acquisition of or difficulty discarding them, regardless of their actual value, leading to clinically significant distress or impairment  in personal, family, social, educational, occupational or other important areas of functioning. Excessive acquisition is characterized by repetitive urges or behaviours related to amassing or buying items. Difficulty discarding possessions is characterized by a perceived need to save items and distress associated with discarding them. Accumulation of possessions results in living spaces becoming cluttered to the point that their use or safety is compromised. It is recognised by the eleventh revision of the International Classification of Diseases (ICD-11) and the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5). Prevalence rates are estimated at 2% to 5% in adults, though the condition typically manifests in childhood with symptoms worsening in advanced age, at which point collected items have grown excessive and family members who would otherwise help to maintain and control the levels of clutter have either died or moved away.People with hoarding disorder commonly live with other complex and/or psychological disorders such as depression, anxiety, obsessive compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD). Other factors often associated with hoarding include alcohol dependence and paranoid, schizotypal and avoidance traits. Differential diagnosis
Collecting and hoarding may seem similar, but there are distinct characteristics that set the behaviors apart.