To expand on the several previous explanations:
In the US:
There seems to be many flavors of "Bachelor of Science degree" from US colleges and universities. There exists an organization that verifies the curriculum for the school,
. If the school is "ABET accredited" then it's engineering curriculum is recognized to meet certain standards. "Engineering degrees" from non-ABET accredited schools are...well...something else.
You would have to determine if there is any equivalency between your Argentinian university curriculum and ABET schools.
Often, but not always, new graduates will take the Fundamentals of Engineering "FE" exam. This helps prove that you actually learned something during your education period and didn't drink too much beer. If you pass the FE, then you may receive the designation of "Engineer In Training" ("EIT").
To achieve "Professional Engineer" ("PE") status, you must have EIT and have four years of work supervised by another PE. With this, you may take the Professional Engineering Exam in your desired field. Pass that test, then you can be a Licensed Professional Engineer and place the "P.E." after your name, stamp engineering drawings, and so forth. Licenses are administered by each State, and the engineer may practice as a PE in that State only. The State may have "reciprocity" rules with other States. Meaning your exam and PE designation in State A will be valid in State B, as long as you pay your license money to State B.
But the reality in the US is that only certain industries & disciplines actually enforce the law of what makes an "engineer" and who may use the title of "engineer". Generally this is Civil Engineering, Structural Engineering, and certain aspects of Mechanical Engineering and Electrical Engineering. A PE is needed to perform engineering work that affects the public welfare, like bridges, building, HVAC, power distribution, etc. It is rare that a PE is required by the employer for tasks such as machine design or manufacturing engineering. Unfortunately, many times I have seen non-degreed people assigned the title of "engineer".
TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering