ALE is used to support distributed yet integrated processes across several SAP systems whereas EDI is used for the exchange of business documents between the systems of business partners (could be non-SAP systems)
ALE is SAP\'s technology for supporting a distributed environment whereas EDI is a process used for exchange of business documents which now have been given a standard format
Both ALE and EDI require data exchange. An Idoc is a data container which is used for data exchange by both EDI and ALE processes.