A UPC, Universal Product Code, is assigned to every single thing that is sold, including Albums, EPs, etc; inventory and sales are tracked by UPC:
https://www.thesmbguide.com/how-to-get-upc-codes
Most Digital Distributors/Propagators will assign a UPC to your release, if you don't provide them with one, such as DistroKid:
https://distrokid.zendesk.com/hc/en-us/articles/360013534414-How-Do-I-Find-the-UPC-for-My-Release-
Individual Songs are assigned an ISRC Code; this is a Song's Social Security Number.
ISRC Codes are used to track Plays and Streams of Songs and are normally assigned and recorded by:
Label
Artist/Producer
Digital Distributor (CD Baby, DistroKid, Band Camp, etc.)
Registered ISRC Code Manager
NOTE: Each Version of a Song requires a UNIQUE ISRC Code.
It's easy to apply to be either an ISRC Code Manager, someone that can ASSIGN Codes to OTHER people's Songs, or as an Individual, assigning Codes ONLY to their own work.
NOTE: There are ANNUAL Registration/Renewal Fees of approximately $100 to $200 to assign ISRC Codes.
Again, All Digital Distributors / Propagators will assign ISRC Codes upon request, though some may charge a small FEE or offer it as a perk for a particular Package Rate / Tier.
While I no longer assign ISRC Codes, I do EMBED them into Song and Album Metadata, when provided.