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.
Yes
Military members work for a goverment
Mercenaries work for the highest bidder with no loyalty. They are Soldiers of fortune.
Can they do the same things? absolutely. Distinction is there are more ppl joining Military in deperation than Mercenaries groups. Nearly everyone I know who joined Military had the poor orgin story and little choice.
Also mercs may have looser standards to what they wont do. Some countries actually dont punish soldider for not following illegal orders.