"Battle Grade" is what Busse's been calling some recently released knives in SR-101 steel rather than INFI.
"Combat Grade" is what Busse typically calls their regular offerings that aren't "Limited Editions."
"Limited Editions," are typically (if not always) satin finished blades offered for a limited time as a regular offering from Busse.
"Competition Grade" was something that was offered on a few knives several years ago. These knives were basically straight out of the oven, without the decarb removed. Later on, they were offering "Competition Finish", which had the decarb removed, but were otherwise unfinished bare metal blades. By "unfinished," I mean not satin or Double Cut. Competition Finish is no longer offered, even as a special order.
"BIG Satin" (Busse Industrial Grade Satin) is a finish that was offered recently on a few blades in special offers. It's a rougher satin finish, and priced accordingly.
There are also military overruns that are occasionally offered, as well as other variants and custom shop blades. These are typically available at shows and "ganzaaas" A ganzaaa is a first-come-first-served free-for-all that you can read more about through the search function.
Or at least that's my understanding from hanging around here for almost a decade.