There is a reason he is called a structural engineer.

Structural guy will spec out all the materials AND the possibly needed new footings. When replacing a load bearing wall with a beam, the weight (which was carried by the all the studs within that wall) is now transferred to the ends of the beam. If your home is on a slab it very well might entail breaking the floor to pour new footings...and it's not possible if you have a post tension slab.

interesting. I read up on both recently and concluded a structural engineer and architect are both needed. One draws up the plans, the other ensures it is structurally sound. Certainly, your local city hall will examine the structural plans. Many architects work with engineers in a seamless fashion and architects are indeed well versed in engineering. Specialists both.

This isn't rocket surgery. Either guy will get you your stamp without your house falling down.

They both draw up plans. The person who will direct you to what you need is the building dept. Some require an engineer's stamp on this type of work. Some don't. If you live in a place where they don't, the architect may be a good choice....I would recommend that you confirm he has professional liability insurance. If he doesn't, go find an engineer. I very rarely meet a small town architect with insurance. On the other hand, engineers are typically all insured. Also, ask the architect to provide some calculations on this solutions so that you can have them checked by an engineer. If he turns white, or changes the subject, or complains that "experience" is all you need, get an engineer.