Most "democratic socialist" parties are socialist (like the DSP in the US), or have at some point in their history been socialist, or at least see socialism as a desirable long-term goal. But I'm sure there are exceptions. What you really have to do is ask what someone *believes*, not what they call themselves.
Sanders has never run away from the word "socialist", but what he seems to believe in is a strong welfare safety net, labor unions operating in a market economy which allows private profit but with regulatory restrictions on the ability of private entities to externalize costs like pollution. There are plenty of people who would call that "socialist", but most people who just plain call themselves "socialist" wouldn't. What he wants is for the US to be more like "Nordic model" country such as Sweden or Denmark. Maybe that's not your personal idea of political paradise, but it's a hell of a long way from North Korea.
As to why Sanders would call himself a socialist, it may be that's what he calls "socialism", but I think it's because he's a contrarian and gadfly who likes to rile people up but excels at retail politics in a tiny, tiny state. I'm all for his preferred policies, but personally I think he'd be terrible president because he's a self-righteous political prig who'd alienate and undermine any of his allies that didn't toe the line.