Can anyone please tell me the benefits being a physicist or being Mechanical Engineer?
You'll benefit from mechanical engineering if you like mechanical engineering, and vice versa.
Maybe better number of employment positions for the mechanical engineer?
This is a really broad question, so I will give a broad answer. In general, a physicist per se has a doctoral degree and quite a bit of specialization. This field largely has an academic focus, although many physicists work in industry as well, but often doing very different things than their academic counterparts.
Mechanical engineering is a very broad field with many sub-specialties. Many mechanical engineers can find employment with a bachelor's degree alone, although different kinds of opportunities may be available with graduate degrees. The focus here is on industry/business. Engineering is an applied discipline, the idea is to design stuff, make stuff, or test stuff, with the overall goal of making money. In absolute terms, there are many, many more people in this field than in physics.
Thanks guys, really helps me
While there are a lot of parallels in topic materials, engineering is mostly about "solving problems" while under the constraint of budgets and deadlines. Experienced engineers have learned the skills to know which corners can be cut and which design compromises can be made to achieve the (usually) conflicting priorities of budgets & deadlines. There's an old graphic used as a joke, a triangle with words at each vertex (paraphrasing here, but you'll get the essence): quality, time, budget...pick any two.
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