Software Bug Vs Issue. Once logged the bug is reviewed by the concerned person. Usually Development or Test manager.
Bugs are anything that threatens the value of the product while issues are anything that threatens of the value of testing or the value of the project and in particular the value of testing. As far as I can understand task represents unit of work which must be. It considers the significant steps in the Bug Life Cycle.
As I mentioned earlier there is a contradiction in the usage of Bug and Defect.
Bug Severity is the degree of impact that a defect has on the system. Why Does Software Have Bugs. If a developer finds an issue and corrects it by himself in the development phase then its called a defect. The above diagram is quite detailed.