Differences

How are these three different?

Azure AD CSP involves licensing Azure AD through a CSP partner, while non-CSP refers to directly acquiring Azure AD licenses from Microsoft.
In Azure AD Legacy the token created from Cybercns is limited to 90 days whereas, in Azure AD CSP and Non-CSP can be selected from the list to a number of days.

	Azure AD Legacy CSP or Non-CSP	Azure AD (New) CSP or Non-CSP
Application in MS Azure Portal	CyberCNS creates an application in the MS Azure Portal and Partner consents	Partner creates the application in MS Azure Portal by themselves (instructions provided in the documentation here)
Permissions required for the CyberCNS application in MS Azure Portal	Maximum permissions of Read-Write	A minimum set of permissions (Read in most cases, Write only when absolutely required)

Azure AD Legacy

If you already have a Azure AD integration then you could continue with this.