Consultant Engineer vs. Corporate Engineer: What are the key differences?

The question seems to be predicated on the assumption that these job descriptions have a single globally accepted definition - in my experience the reverse is true - I often come across people doing practically the same job in the same organisation that have different job titles, whereas the same job title is often applied to quite different roles and the variation between different organisations is even greater. Details like skill requirements, career progression, job security etc. vary more with the particular organisation (or department), its size, position in the market, internal attitudes and things like the economic cycle and so on.

    - Andy. 

By "corporate engineer", do you simply mean an engineer who works for only one company?

Ok, I'm assuming that (based on the wording of the questions) by "corporate engineer" you mean someone working in a engineering company, and by "consultant engineer" you mean someone working for a consultancy (or self employed as a consultant), These answers are from the perspective that I've done both (and managed teams in both). Albeit in one industry, other industries may vary. 

1. Role focus: Not very different, except that as a consultant you may be working on several different projects at once. Not necessarily, some consultants spend months or years working on a single project for a particular client. In terms of unique value, again not actually that different, on both cases you'll be expected to have some specialist knowledge or skill you can bring, but as a "corporate engineer" it is likely to be easier to develop this. I frequently find that consultants who start as graduates find they need to work in a "corporate" role either permanently or on secondment in order to develop their knowledge, as a consultant you're expected to have that knowledge already.

2. Interpersonal skills are vital in consultancy. In corporate roles it may be possible to hide yourself away, as a consultant you have to be able to communicate well with clients. Equally as a consultant you are likely to need better financial skills, as you almost certainly will get involved in tendering for contracts, but those can typically be learned on the job. As a corporate engineer you can often "just" be an engineer (although you may not progress far like that!).

3. Career progression: No real difference. Theoretically as a consultant you can become self employed and have much higher earning potential, but this is high risk: you only have that potential of people want your skills and knowledge, which can easily become outdated. (When people talk about "over paid consultants" you need to remember that if they work for a consultancy then what the consultancy charges them out at is a LOT more than they get paid! (Because it covers overheads, time we spend working on bidding for work and other unchangeable admin tasks, times when the work is quiet, let alone profit to the shareholders.)

4. Work-Life Balance & Stability: Now this is the big one, and the answer is: it all depends who you're working for, what stage in your career you're at, whether you have a specialist area, what industry you're in, etc etc etc. The least stable role is the self employed consultant, as above you only have work if people want your skills at that time. And while this role can have the best work-life balance if you're one of the very lucky minority well enough known to pick and choose your work, but for many it can be the worst as you always have to be chasing the next job. If you're a "corporate engineer" or work for a consultancy then it all depends on your employer (and indeed your particular line manager), and can vary a lot. It is often easier to achieve flexible working if you work for a consultancy rather than as a "corporate engineer" as the nature of the work is that you're typically providing services intermittently to each client, so it can be easier to fit those around other life - this is why many of us move into consultancy as we near retirement. (I plan soon to be one of the many retired consultants who works some hours in winter months but somewhat disappears form view once the sun comes out!) In terms of project timelines and travel, that's driven by the industry and role, so can't be said to be different for one or the other.

5. Professional Development: I would say that consultancy is often better for developing business skills and interpersonal skills for the reasons given above, it's also good for developing general industry knowledge in your industry as you work with a range of clients. I would say, as above, that "corporate engineering" is a better place to develop technical skills - clients don't expect to have to pay consultants to learn to do the job! Regarding training and certification etc, again that depends much more on the employer than the role.

What you haven't explained is why you are asking? That might help give clearer answers.

P.S. I've got a standard talk I give to our graduate consultants when they start, and the first point I make is that when I was working in industry I tried as hard as I could to never use consultants. For anyone thinking of moving into consultancy it's important to remember that. No-one wants to employ a consultant, sometimes they just have to for legal compliance reasons or because there's a bit of skill that's not needed often enough to justify it in a permanent member of staff. So what they want you to do is to come and go as quickly, cheaply, and with at least fuss as possible. If you're going to be successful in that world you've got to make yourself someone the client actually wants back again.