Appllicants can be in or outside of Australia to apply for any of these visas. You have an option to be sponsored by an employer under direct stream or you can chose transition stream as explained below:
Temporary Work (Skilled) visa (subclass 457)
The Temporary Work (Skilled) visa (subclass 457) allows skilled workers to come to Australia and work for an approved business for up to four years. You must be sponsored by an approved business. A business can sponsor someone for this visa if they cannot find an Australian citizen or permanent resident to do the skilled work. You can be in or outside Australia when you lodge your application.
Employer Nomination Scheme (subclass 186)
The Employer Nomination Scheme visa (subclass 186) is for skilled workers who want to work in Australia. This visa involves a two-step process, firstly, nomination by an approved Australian employer and then an application under the nominated stream. It is part of the Permanent Employer Sponsored Visa programme. This visa is a permanent residence visa. You can be in or outside Australia when you apply. If you are in Australia, you must hold a substantive visa or a bridging visa A, B or C. The Temporary Residence Transition stream is for subclass 457 visa holders who have worked for two years, while holding a subclass 457 visa, in the same occupation with their nominating employer (who is not subject to a labour agreement and who has lodged a valid nomination with us under the Temporary Residence Transition stream), who wants to offer them a permanent position in that occupation. The Direct Entry stream is for people who have been nominated by their employer under the Direct Entry stream, people who have never, or only briefly, worked in Australia, or temporary residents who do not qualify for the Temporary Residence Transition stream. The Agreement stream is for subclass 457 visa holders sponsored by an employer through a labour agreement.
Regional Sponsored Migration Scheme visa (subclass 187)
This visa is a permanent residence visa for skilled workers who want to work in regional Australia. It allows you to work in Australia under one of three streams: the Temporary Residence Transition stream, the Direct Entry stream or the Agreement stream. You might be able to get this visa if you:have been nominated by an approved Australian employer for a job in regional Australia (regional Australia does not include the Gold Coast, Brisbane, Newcastle, Sydney, Wollongong or Melbourne), are younger than 50 years of age, unless you are exempt, meet the skills, qualifications and English language requirements, unless you are exempt and apply under the stream for which you were nominated.