The attack ads from this appearance on Meet the Press write themselves https://www.washingtonpost.com/news/the-fix/wp/2015/10/12/why-bernie-sanders-isnt-going-to-be-president-in-5-words/
Meet the Press ✔ @meetthepress
CHUCK TODD: Are you a capitalist?@BernieSanders: No. I'm a Democratic Socialist.
8:33 AM - 11 Oct 2015
And, in those five words, Sanders showed why no matter how much energy there is for him on the liberal left he isn't getting elected president.
Why? Because Democrat or Republican (or independent), capitalism remains a pretty popular concept especially when compared to socialism.
A 2011 Pew Research Center survey showed that 50 percent of people had a favorable view of capitalism, while 40 percent had an unfavorable one. Of socialism, just three in 10 had a positive opinion, while 61 percent saw it in a negative light.
Wrote Pew in a memo analyzing the results:
Of these terms, socialism is the more politically polarizing the reaction is almost universally negative among conservatives, while generally positive among liberals. While there are substantial differences in how liberals and conservatives think of capitalism, the gaps are far narrower.
...The simple political fact is that if Sanders did ever manage to win the Democratic presidential nomination a long shot but far from a no shot at this point
Republicans would simply clip Sanders's answer to Todd above and put it in a 30-second TV ad. That would, almost certainly, be the end of Sanders's viability in a general election.
Americans might be increasingly aware of the economic inequality in the country and increasingly suspicious of so-called vulture capitalism all of which has helped fuel Sanders's rise. But we are not electing someone who is an avowed socialist to the nation's top political job. Just ain't happening.
You can try to argue that the two terms are not the same but that will not stop the Kochs from running $200 milion to $300 million using that term in negative ads that would be very effective.