A 457 Plan is very similar to a 401k plan and a 403b plan.
These plans are generally offered to government employees (state and local) and some tax-exempt organizations. These plans are commonly called non-qualified deferred compensation plans.
A non-qualified plan is an employer sponsored plan that does not meet the tax qualification requirements under Internal Revenue Code Sec 401(Qualified Plan Requirements). Many retirement plans are non-qualified includings SEP, SIMPLE and Tax Sheltered Annuities (TSA). These type of plans are governed by their own rules.
401k, 403b, 457 and Roth 401k
Tax Year Under Age 50 Above Age 50
2016 $17,500 $23,000
2017 $18,000 $24,000