For distinguishing grades of carbon steel, you have to know Carbon content. Sounds simplistic & easy; it's not. XRF - xray fluorescence - 'gun' cannot give Carbon [or Nitrogen]. So you have to go to a more physical test - these machines used to use a spark, and left an 'arc strike' to deal with. Current ones use plasma or laser, so you get left with a small, smooth divot. I usually refer to this as 'semi-nondestructive' testing. The fitting/pipe is slightly marred, but usually nobody worries about a small, smooth blemish.
Also, it doesn't about multiple certifications. Ignore all of the overlapping ones except the one you need. Either the material in question meets that spec, or it doesn't. In my experience, the off-spec materials have been 5- and 9-Chrome [too lean], 316 stainless [too lean, too little Molly], and gold wedding rings [12-karat, instead of 18-k].