In this case the white label drive is used recertified/refurbished by Seagate, which is why the seller states it has 0 bad sectors and correctly doesn't state it's new.
White label drives can also be binned drives directly from the manufacturer that didn't meet the full specs to be sold as full retail. 2nd tier drives are usually used in their own externals. 3rd tier drives are sold to resellers.
The green label drive is new, but OEM, which again the seller correctly states. OEM drives are bought in bulk and may have different specs than the retail drives.
Both drives are warranted my the seller. Which isn't necessarily a bad thing as long a the seller is around to honor it.
The Newegg drive is new, but sold by GoHardDrive, which I personally don't hold in high regard because of some negative comments here and elsewhere and their association their sister companies, MDD (MaxDigitalData) and Avolusion which are reported to have sold used drives as new.