Final answer:
The primary difference between Amazon S3 and Amazon Glacier access is that S3 offers immediate access to data, while Glacier has a delay in retrieval.
Step-by-step explanation:
The primary difference between Amazon S3 and Amazon Glacier access is that S3 offers immediate access to data, while Glacier has a delay in retrieval. S3 is designed for real-time data processing, making it ideal for applications that require quick access to information. On the other hand, Glacier is primarily used for archival purposes, where the data retrieval time can take hours or even days.