They are standardized steel designations, not brand names. 1095 is an AISI carbon steel: the 10 means plain carbon and the 95 means roughly 0.95% carbon. 420HC is a stainless grade, the HC standing for high carbon, a higher-carbon version of AISI 420. Each name encodes a composition.
In the AISI four-digit system for carbon steels, the first two digits identify the alloy family and the last two give the carbon content in hundredths of a percent. So 1095 is plain carbon steel at about 0.95% carbon, and 1084 is the same family at 0.84%.
Stainless grades follow different series. The 400 series covers the martensitic stainless steels used for knives, which is why 420, 440A and 440C all appear on blades.
Chinese GB designations like 8Cr13MoV read almost literally: 8 for roughly 0.8% carbon, Cr13 for about 13% chromium, MoV for molybdenum and vanadium additions. Once you know that, 3Cr13 and 9Cr18MoV tell you their own story.
Japanese and proprietary names such as VG-10, AUS-8 and the CPM steels are trade designations rather than coded compositions.
Heat treat. The same designation on two knives can perform very differently, which is why the verified steel records single out Buck's proprietary heat treat as what sets Buck's 420HC apart from generic 420.
It also tells you nothing about grind, which affects real cutting more than alloy does.
The full reference entry, with the published composition and hardness range and every listing we carry in it, is 420HC in the Steel Lab.