Every object contains three things:
Source The data itself, the metadata which is defined by whoever creates the object storage; it contains contextual information about what the data is, what it should be used for, its confidentiality, or anything else that is relevant to the way in which the data is used and a globally unique identifier. The identifier is an address given to the object in order for the object to be found over a distributed system. This way, it’s possible to find the data without having to know the physical location of the data.
With block storage, files are split into evenly sized blocks of data, each with its own address but with no additional information (metadata) to provide more context for what that block of data is. (Oracle DB Blocks/SAN Arrays etc.)
Object storage, by contrast, doesn’t split files up into raw blocks of data. Instead, entire clumps of data are stored in, yes, an object that contains the data, metadata, and the unique identifier.