What is the difference between symbiosis and mutualism?

Question

What is the difference between symbiosis and mutualism?

Answer 1

Mutualism is a form of Symbiosis; Symbiosis includes Mutualism, Commensalism and Parasitism

Where in mutualism both organisms benefit, in Commensalism one benefits but the other isn't adversely affected and Parasitism where one benefits and the other is harmed.  

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Answer 2

The term symbiosis (from the Greek: σύν syn "with"; and βίωσις biosis "living") commonly describes close and often long-term interactions between different biological species. The term was first used in 1879 by the German mycologist, Heinrich Anton de Bary, who defined it as: "the living together of unlike organisms".

The definition of symbiosis is in flux and the term has been applied to a wide range of biological interactions. The symbiotic relationship may be categorized as being mutualistic, parasitic, or commensal in nature [4][5]. Others define it more narrowly, as only those relationships from which both organisms benefit, in which case it would be synonymous with mutualism.

Symbiotic relationships included those associations in which one organisms lives on another (ectosymbiosis, such as mistletoe), or where one partner lives inside another (endosymbiosis, such as lactobacilli and other bacteria in humans or zooxanthelles in corals). Symbiotic relationships may be either obligate, i.e., necessary to the survival of at least one of the organisms involved, or facultative, where the relationship is beneficial but not essential to survival of the organisms.

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Mutualism is a biological interaction between individuals of two different species, where both individuals derive a fitness benefit, for example increased survivorship. Similar interactions within a species are known as co-operation. It can be contrasted with interspecific competition, in which both species experience reduced fitness, and exploitation, in which one species benefits at the expense of the other. Mutualism and symbiosis are sometimes used as if they are synonymous, but this is strictly incorrect: symbiosis is a broad category, defined to include relationships which are mutualistic, parasitic or commensal. Mutualism is therefore only one type of symbiosis.

Mutualism plays a key part in ecology and evolutionary biology. For example, mutualistic interactions are vital for terrestrial ecosystem function as more than 70% of land plants rely on mycorrhizal relationships with fungi to provide them with inorganic compounds and trace elements. In addition, mutualism has driven the evolution of much of the biological diversity we see, such as flower forms (important for pollination mutualisms) and co-evolution between groups of species However mutualism has historically received less attention than other interactions such as predation and parasitism.

Measuring the exact fitness benefit to the individuals is not always straightforward, particularly when the individuals can receive benefits from a range of species, for example most plant-pollinator mutualisms. It is therefore common to categorise mutualisms according to the closeness of the association, using terms such as obligate versus facultative. Defining "closeness", however, is also problematical. It can refer to mutual dependency (the species cannot live without one another) or the biological intimacy of the relationship in relation to physical closeness (e.g. one species living within the tissues of the other species).