Complex sentence: Decline refers to the degenerating of something whereas obsolete refers to the outdating of something or that it is no longer in use.Is the prosses of declining, a gradual sinking and wasting away.
Split into simpler sentences: Decline refers to the degenerating of something whereas obsolete refers to the outdating of something or that it is no longer in use. It is the process of declining, a gradual sinking and wasting away.