Oxblood is oxblood, as you say, even though there may be a few variants. All the rest, Blueblood, Blue Eggyolk Oxblood, Blue Oxblood, etc., are just names of a particular type of marble that has oxblood on it. Having said that, I have seen people use some pretty creative terms for marketing purposes - usually in an effort to call something that is not oxblood, oxblood. lol