In short, headshots- one word, have a very specific purpose, market, style and end goal, as apposed to a general portrait.
Headshots were and still are originally for actors. It was used as an actors calling card in auditions. The actor gives their headshot & resume to the casting director, so they can reference it when deciding on the cast. It's first used to get actors in the door to even get the audition. This is the be all, end all, picture that someone sees to decide whether or not you're right for the role.
The purpose of them was to sell themselves, to show themselves in the best light, and often in contrasting ways so you could see them smiling and serious, or good guy bad guy, or comedy or drama.
As times have changed, actors still absolutely need headshots, but who else does is the business professional.
Now everything lives online. Like casting directors choosing actors from a picture on a screen to give them a test, people- aka the market, is choosing who they hire and work with the same way.
This is especially true for people like: Realtors, Insurance Agents, Lawyers, Coaches, or
anybody trying to sell themselves as a part of their business. It's crucial. Do they need a serious and a smiling? No. Do they need 4 outfit changes, lighting changes, and complete vibe changes to make them feel more like a certain character or genre, no.
But they do need a purposively headshot. Most people do. If you're on LinkedIn looking for a job, it helps if you have a professional looking photo of yourself to nail the job.
On the contrary, you don't need to wear a suit, if your job doesn't require one, or the only time you pull one out is for weddings, photos and funerals.
The purpose of a headshot is to sell you. Often, the real you. You're often trying to reach a certain market too, and helps if you kind of dress the part. And it says a lot about your business too.
Wear a suit sure, but if you're selling to blue collar workers or small business owner millennials, then it may or may not sell well. Depends on your market, but authenticity sells.
So, headshots are a little involved. They're not just a close-up portrait. They're their own thing, and require a helpful hand to get it right.
Also, lighting them, is a whole other blog post.