Temporary Work (Skilled) or 457 visa allows businesses based either in Australia or overseas to sponsor workers for a temporary visa lasting up to 4 years. Only certain occupations are eligible for 457 visas, and employees must be paid at the market rate.
The RSMS visa requires a job offer in a regional area. The position needs to be approved by a Regional Certifying Body, but otherwise the skill level criteria are lower than for an ENS visa. The resulting RSMS visa is a permanent visa, but is subject to cancellation if the employee leaves employment within 2 years of obtaining the visa.
The Employer Nomination Scheme is a permanent visa, and requires the nominating employer to be operating in Australia. The employee needs to show a higher level of skill than for a 457 visa, but otherwise the criteria are broadly similar to the 457 visa.