Before discussing the technical differences, I must interject regarding data privacy.
Whether you use GetAttribute or GetParticipantData, you must be extremely cautious about extracting Personally Identifiable Information (PII) from the call flow. If these variables are printed into the Architect execution logs without the ‘Secure’ flag enabled, you are violating GDPR logging principles.
GetAttribute is a legacy function left over from the very early days of the platform.
You should always use GetParticipantData or the built-in Call.ParticipantData string collection variables. The modern participant data architecture binds the attributes directly to the conversation object, whereas the legacy attribute functions often failed to persist data across complex SIP transfers and consult legs.