The Immigrant Visa and Adjustment of Status applications essentially are the same procedure.  They permit the appropriate governmental authority to determine if you are morally and physically fit to be admitted to the United States as a lawful permanent resident. This is the final step of the Green Card process – approval of an Adjustment of Status application or admission to the United States of the holder of a valid Immigrant Visa brings about lawful permanent resident status.
In the course of either application, you will be fingerprinted and required to undergo a medical examination. Immigrant Visa applicants will be called to an interview, but this usually does not happen for Adjustment of Status cases. 
The principal difference between the two types of application is location. Immigrant Visa processing takes place via a U.S. consular post overseas, whereas Adjustment of Status processing takes place here in the United States. I mention both types of application because it occasionally can be quicker to be admitted to the United States on an Immigrant Visa than it is to wait for the completion of Adjustment of Status. However, it obviously would be more convenient for you to be able to adjust status in the United States, because that will avoid the long and expensive trip home to your local U.S. consular post. 
You also can apply for separate permission to work and permission to travel overseas through the filing of an Adjustment of Status application.
Application Fees
Immigrant Visa processing will vary according to the type of case (Family-Based or employment-based).  Adjustment of Status fees increased to $1,225 per adult applicant (and $750 per child applicantaged under 14).
Immigrant Visa Availability
Nevertheless, please note that you only will be able to apply for an Immigrant Visa or to adjust status once an Immigrant Visa becomes available to you. Immigrant Visa availability depends both on your country and the qualifications required for your position. You will need to check with the Department of State’s monthly Visa Bulletin for Immigrant Visa Availability.
After an Immigrant Visa becomes available, an application for an Immigrant Visa or for Adjustment of Status can be made. An Immigrant Visa must continue to be available after filing for each month that the case is being processed, in order for the case to advance to approval; if an Immigrant Visa is unavailable in any given month, processing will be suspended until an Immigrant Visa becomes available.
Adjustment of Status: Maintenance of Nonimmigrant Status
If you are adjusting status, you should try to remain in your valid nonimmigrant status. You can fall out of nonimmigrant status for up to 180 days and still be eligible to adjust status, but no time at all out of status is preferable because no one can guarantee that your case would be approved within the 180 day period. If you spend more than 180 days out of status, your Adjustment of Status application will be denied and you will have to apply for an Immigrant Visa.
Adjustment of Status: Change of Employers
Should you wish to change employers, you would need to begin the whole Green Card Application process again, unless your sponsoring employer agrees to keep your application alive or unless have reached the stage in the process whereby your Adjustment of Status application has been pending for 180 days or longer.
Adjustment of Status: Dependents
If applicable, your dependents would need to file separate Immigrant Visa or Adjustment of Status applications with a separate set of fees, to immigrate. Their applications could be made at the same time as yours when an Immigrant Visa becomes available, and they would undergo the same procedures during those applications as you would.
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