"So I've seen references to the banishing and invoking earth pentagrams,"

Remember that in the generic Lesser Ritual of the Pentagram you're not invoking/banishing the element Earth in particular; it's just that the pentagrams are drawn the same way.

"but I don't know the difference between the two in the case of when to perform either one and am I correct that the banishing is the LBRP and the invoking is the LRP?"

L.R.P. = Lesser Ritual of the Pentagram (generic name: can be either)
L.B.R.P. = Lesser Banishing Ritual of the Pentagram

By banishing you ground yourself, get rid of unwanted "stuff" and as a whole purify the space. By invoking you sort of go upwards, light yourself up and call forth generic spiritual energy, so to speak. (That doesn't mean there isn't a purification and an influx of LVX in both; there is. It's just that they go in different "ways.")