>>3802699As with many mythological creatures, it doesn't really refer to a single well-defined creature as much as a general type of creatures. Goblins were small, mischievous spirits or fairies. "Hob" refers to household spirits. So Hobgoblins are Goblins who live in or near people's homes and are generally benevolent as long as you don't do anything to offend them.
In D&D, which seems to be what the OP is referring to judging from his picture, Hobgoblins are completely different. They're still related to Goblins, but they're an entirely separate subspecies that's bigger, stronger and smarter. They have a highly organized and militarized society compared to the Goblins' chaotic tribes, but they're still evil creatures.