horizontal mobility

movement from one position to another within the same social level, as changing jobs without altering occupational status, or moving between social groups having the same social status.

cultural diffusion within the same social level, as the spread of fashion within one economic class.

sociol the movement of groups or individuals to positions that differ from those previously held but do not involve any change in class, status, or power: Compare vertical mobility See also upward mobility, downward mobility