87430 vs 87880

I need help. We have always coded 87430 for rapid strep. Now our new billing dept says it should be 87880. The CPT® book is somewhat vague. It just says 87430 Streptococcus group A. The 87880 says Streptococcus A. The only difference I find is on the internet. 87430 says "Enzyme Immunoassay" and the 87880 says "Immunoassay" with direct optical observation. Which is the correct one to use for doing a rapid strep in the office and what is the difference between "Enzyme Immunoassay", and just "Immunoassay"? Thanks