If you sign up to kill people, and it’s not in reaction to an attack on your country, you are by definition just a mercenary. I don’t wish death on you, but I don’t feel much when you die and I don’t think you deserve any special consideration by society for your questionable career choice.
But they aren’t, by definition.
A person paid by a government to follow orders and enact violence upon a target or targets chosen by the authorities in that government… Am I describing a member of the military or a contractor for a PMC like Academi? It’s a legal distinction without a functional difference, like a corporation vs an LLC. There are limited circumstances where, in a court, they are treated differently but the product that comes from them and the processes by which it is produced are essentially the same.
Mercenary hired to kill for monetary gain. How’s that different than a soldier? Source of payment?
So here’s the answer to your question