Big aerospace defense companies

In general, for entry level engineers, is there any significant difference between Boeing, Lockheed, Raytheon, etc.? Assuming similar pay, duties, etc., how does one determine which company might be best to start their career?

Any opinions of specific companies would be appreciated.

There are lots of differences, just like there are in any industry. When I was interviewing at Raytheon you were hired directly into a specific job, Lockheed had a rigid rotational program for new hires, and Northrop Grumman had a flexible rotational program where you essentially got to tour the company for 2 years. Lockheed had me watch videos of the CEO, Northrop had a panel with candidates, recent new hires, and NO managers so that we could get the straight dope on the company.

Apply, interview, the differences start to become apparent.

Yes, there are lots of differences. Some of those differences may be apparent during the interview process a but a lot of those differences will not. For example: In some companies, it takes an aggressive personality to succeed others more technical smarts. There are many other differences. You will only find out when you start working there and observe the culture for a while.

You will, of course, have to develop your own style, which will be influenced by your environment, which is that of the company you are working for.

If you don’t like where you are working, switching jobs early in your career to find a better fit is common.