The hydration that soap can provide is an essential thing. Liquid soap dries the skin less than the solid soap. However, there are solid soaps types containing moisturizing oil (as the olive oil) that are good for our skin. Current soap cleanse the skin of dirt and food through various substances they contain, such as Shea butter. Some products are so good that you no longer need to apply body lotions in order to moisturize the skin after showering.
Some types of solid soaps have scrubbing properties. There are liquid soaps created for exfoliation too, but in this case you have to use a special glove for massaging. Liquid soaps have the advantage of containing salicylic or glycolic acid, which provide effective long-term exfoliation and skin rejuvenation.
Solid soap has a discreet perfume compared with the liquid soap, which is especially helpful for sensitive skin. A very fragrant soap can be a bad choice because it will combine with the fragrant smell of our perfume.
A big solid soap disadvantage is that it can contain bacteria or fungi on its wet surface, which will be transmitted to other people if the soap is shared. From this point of view, liquid soap is more hygienic. Liquid soap is usually used with a sponge or with a washing glove (which must be well rinsed and dried thereafter, in order to avoid bacteria accumulation).