App1: Access keys -
App2: Shared access signature (SAS)
A shared access signature (SAS) provides secure delegated access to resources in your storage account without compromising the security of your data. With a
SAS, you have granular control over how a client can access your data. You can control what resources the client may access, what permissions they have on those resources, and how long the SAS is valid, among other parameters.
Reference:
https://docs.microsoft.com/en-us/azure/storage/common/storage-sas-overview