While both laundering and hand washing are also water-based and require detergents, they are not the same as wet cleaning.  Laundering uses standard washers and dryers to clean certain non-delicate garments.  The settings on these machines are preset, with only the amount of detergent being roughly controlled.  Hand washing on the other hand, is limited to delicate garments and cannot be performed in volumes as it is labor-intensive.  

In comparison, wet cleaning is a high volume process that uses milder detergents than traditional home laundry products.  Water and solvent levels are precisely measured and tailored to fit each garment's specific needs.