How is this different from an assessment vendor like HackerRank or CodeSignal?

Point-solution assessment vendors run a test. Workera runs the engine: the assessment is one of four agents on a single Capability Score that hires, develops, mobilizes, promotes, and certifies on the same skill graph. The score from hiring is the score that develops the employee three years later. Comparable across roles, comparable across time. A point solution cannot do that by definition.