Comment by _delirium

That difference is partly due to different things being valued: Walmart's valuation is primarily its current business, while Amazon's valuation is primarily its future growth prospects. That future growth is valued in the market cap today, but its actual materialization will only take place in the future, so doesn't show up on the payroll today. If Amazon does actually succeed in growing to Wal-Mart levels of sales, it will end up with a lot more employees than it currently has, though quite possibly still fewer than Wal-Mart.