The G-49 17.5cm and the G-50 20cm are both Chinese chef's knives, whilst they look like cleavers, they are not suitable for this task. These rectangular knives, referred to in Chinese as Caidao are multipurpose knives. Chinese people and chef's will use these knives in the same way that Western chef's will use Western style chef's knives, such as the G-2. These knives will be typically used to prepare all kinds of meat and fish. In fact it is typically the ONLY knife that a Chinese chef will use. Whilst the Chinese chef's knife resembles a cleaver, it does in fact have a sharp thin blade like a standard G series knife. The G-49 is a typical Chinese Caidao with a 2.2mm thick blade and if used as a cleaver, the blade will usually get damaged. Different parts of the blade are used for different tasks with the front of the blade used for a tapping cutting stroke, the middle and back of the knife for heavier chopping work. Whilst it may seem awkward those skilled with a Chinese blade can use them for any kitchen task.
The G-50 whilst also a Chinese chef's knife has a much thicker 4.0mm blade and is known as a Gudao in Chinese, or Chinese chopper. These choppers are more likely to be used for chopping vegetables, maybe cutting through some softer bones and mincing meat.
In China these knives are literally used for everything and if you are lucky enough to go to a Peking Duck restaurant you will even see the waiter's carving duck meat with these knives.