Human resource development and human resource management levers for sustained competitive advantage: Combining isomorphism and differentiationHuman resource development (HRD) and human resource management (HRM) practices have increased in importance (Alagaraja, 2014), moving from ancillary functions to a collective central component of a firm’s strategic objectives. Much research now focuses on the human capital of an organization as a source of competitive advantage (Wright & McMahan, 1992; Lado & Wilson, 1994; Barney & Wright, 1998; Wright, Dunford, & Snell, 2001; Liu, van Jaarsveld, Batt, & Frost, 2014). This is amplified by the migration of business from manufacturing to service or more human capital-intensive enterprises. The crucial role of human resources has resulted in the evolution of reliance on employee relations for the achievement of strategic objectives and firm performance