Durkheim's organic and mechanic solidarity compared to Tonnies Gemienschaft and Geseuschaft is that the solidarity is based on the dependence and how society works together whereas Tonnies theory is how the society gets together more emotionally and how everyone gets along. Both of these are apart of the social evolution. They are the key to how the society interacts today.
Organic solidarity is the social cohesion based upon the dependence individuals in more advanced society have on each other. Individuals perform different tasks through labor with different values and interests. The society depends on each other to make sure the specific task is done by the individual. Mechanic solidarity is the social cohesion based upon the likeness and similarities among individuals in a society, and largely dependent on common rituals and routines. Durkheim's theory on social solidarity is the bond between all individuals within a society. Mechanic solidarity as Durkheim described it was when all the individuals performed the same tasks as all the others in the society.
For example if someone were to die, the society would still run properly and not change because everyone is doing the same tasks. It basically is the dependence on the total social system not the individual itself. Organic solidarity as he described individuals no longer performs the same task. They perform certain specific functions; rely on the well being and successful performance of other individuals. For example if one person fails, the rest of them fail as well. All this ties into social evolution because it's all the society works today.
Gemeinschaft is a type of society in which life is intimate; a community in which everyone knows everyone else and people share a sense of togetherness. In order to have this, the people are going to have to want this...