Security guards come in three basic flavors: laughable, secretarial, and terrifying. Laughable are the stereotypical mall guards, overweight, balding, wearing an ill-fitting uniform, and enforcing arbitrary authority with limited success. Secretarial are a step up, where they are secure in their role and their interactions with the public, and look the part. I named it secretarial in part because of the setup at my building: guards cover for the receptionist on her breaks. Its also a general reference to the substantial amount of paperwork and procedure involved in the industry, which I find best expressed at this level. Terrifying is your Blackwater et al. These are not really like most domestic security companies, in that they have substantially different training requirements, and with a very different appeal to both employees and customers. Nevertheless, the two branches are technically part of the same industry.
These are not meant to be exclusive categories. I certainly have my laughable moments (possibly including right now), as do all of my fellows. Also, there are good number of the flex officers that I work with who do, on occaision, work armed accounts. While I would still basically qualify them as secretarial, there is an edge of the terrifying there. Especially when one of them says "I am going to be tired, surly, and ARMED" while bitching about the crappy schedule they have in the upcoming week.