Anything that a firm does especially well compared to rival firms is referred to as:

The term that describes anything a firm does exceptionally well in comparison to rival firms is "competitive advantage." This concept encapsulates the unique strengths that allow a company to outperform its competitors. When a firm has a competitive advantage, it can create more value for its customers or operate at a lower cost than its rivals, thereby achieving superior performance in the marketplace.

Competitive advantage can stem from various factors, such as innovative technology, superior quality, customer service, brand reputation, or operational efficiencies. It is essential for long-term success, as it helps the firm establish a strong market position and defend itself against competitors. When businesses are able to leverage these advantages effectively, they can achieve higher profitability and market share.

The other options refer to concepts that, while related to competitive dynamics, do not specifically denote the exceptional capabilities of a firm compared to its rivals in such direct terms. 'Market positioning' focuses on how a firm positions itself in the marketplace relative to competitors and customers. 'Strategic leverage' is more about utilizing resources and capabilities strategically rather than highlighting performance superiority. 'Core competency' refers to a firm's unique strengths or resource bundles that provide a competitive edge but isn't synonymous with the broader concept of being better than rivals.