I think they are the same . Its more to do with marketing than actual functioning of the product. Although I haven't tried any product labelled as Facial cleanser recently,I guess cleanser would foam less than a typical face wash,hence making it look more Gentle .
Both are different Cleanser is used to clean your mack up, dead cell or any external pollution dirt and it has moisturising agent Face wash can be a replacement of soap it is topical cleaner....... after one year i replayed may be useful for some one)