Overall, Sweden didn't fare worse than other European countries with harder measures. But these things are really difficult to compare due to geographic and cultural issues. Sweden is quite rural. Swedes value personal distance, and from my limited experience they easily more readily conform to rules and social norms, so I would assume there was less close contact, and better adherence to the few rules given out.

The US btw. also is largely rural/sub-urban, which should significantly reduce the risk of infection. I think almost all of my colds and flues I got on the metro or the overcrowded super-market.