Despite the admonishments that the term is "just" Vaquero for the large-frame guns, "old" (small case) is indeed appropriate now - what with Ruger's odd labeling of the .44 Specials as "just" Vaqueros also.
As is mentioned frequentlky here, either way, leave the term "model" (either lower or upper case) out of the discussion entirely as that just gets folks into another dither, appropriately I might add.
The original, large frame Vaquero is, to me, now either "original," "old," "older," or "large." The .44 Special is, indeed, technically a New Vaquero, despite what it says on the frame. For the NV, I don't use the term "small" to describe (but instead "mid-frame") as some folks - inaccurately - think ".32 H&R Single Six," not helped by the fact many folks informally refer to the .32s as Baby Vaqueros or Vaqueritos. I am guilty of using the latter as it truly is just a nickname. But then, again, not everyone knows that either!