The two concepts are not interchangeable. Otherwise, we might also say that fascism and capitalism are interchangeable.
To answer the question: Social-democracy. But that completely depends on one's definition of those concepts. Many would not think of as Soviet-Russia as a proper example of communism, let alone socialism. if you think of socialism as a philosophy where the principle is to have high solidarity between the classes than most of Western Europe, Japan, British Commonwealth is socialist. And distinguish between the Rhineland model (co-operation) and Anglo-Saxon (conflict) model.
Also, what's your measure of success? Onw can make a good case that present day America is an abject failure, because it doesn't manage to provide even basic functions to as much people as possible. 20 percent of Americans live under the poverty line, inter-generational undernutrition is a real problem and check out obesity in West-Virginia. In many respects, Cuba is more successful than America (except for big box stores and 72 kinds of cereal...of course. Which, incidentally is a waste of resources.)
As long as countries like Costa Rica and Czechia manage to beat you with regards to ANY social indicator, with HALF the wealth or less, you're failing as a country.
Suggestions for improvement of the question:
This association you speak of was limited only to (rightwing) America. Did not exist in Europe, "socialism" is a perfectly acceptable 'ism'. Same goes for communism. There were/are many communist parties in Western-Europe.
Your question is also leading on two other points: That of 'total failure':
- China is a resounding success, while being a one-party rule communist state, personality cult and 5 year plans and all. Also: Universal health care! (if that doesn't make them 'socialist' ....)
- Whether Soviet-Russia was a good application of socialism/communism is highly debatable.
- The world wide financial crashes of 1929, 1997 and 2008 speak against the American extremist capitalism as a model of success, as well as the fact that America performs so miserably on so many essential social indicators: teen pregnancy ishas been 10 times higher than Europe for decades (https://www.sfgate.com/news/article/U-S-teen-birth-rate-higher-than-Western-Europe-s-2462254.php), poverty is much higher, health care is FAR worse. Nobody in Europe dies because of lack of health care, in America: 45.000 people per year. America is a good country for millionaires, but not for the poor or the middle class. The poor run the risk of serving 25 to life for merely shoplifting (https://bit.ly/3F9cEor) Caveat: It's also good for those earning more than $150-200K, provided of course, they're not black nor Hispanic. Caveat two: it's also not a good country for millionairs of color who dare to speak out. Same goes for white women, but somewhat lesser: their risk for street executions of the cop kind (with impunity) are virtually zero.