SAP WM is now a part of SAP Logistics execution module and has undergone several releases from the first time it was introduced by SAP as a independant warehouse solution in the R/2 environment. From 2006 we see it in its most developed form as a part of LES which is available as release ECC 6.0 .
SAP eWM is similar to SAP WM functionality but with more flexibility in customising like the warehouse structure or picking/put away processes. Also new concepts like activity areas, Work Centers, and Resources are incorporated into SAP EWM .
As per SAP , eWM is not projected as a replacement to WM but more as a robust and flexible alternative to WM .
From what I could understand ,here I will compare both the solutions in terms of their functionalites that are available in the versions ECC 6.0 for WM and EWM 7.0 for eWM
From System documents perspective :
WM has Transfer requests and Transfer orders .Transfer orders are the actual work orders based on which the stock movement takes place withing a warehouse .
eWM has a slightly different presentation of these documents .eWM has Warehouse order which is similar to a WM Transfer order and further a Warehouse task which is similar to Transfer order line item.
In WM movement types that determine the shipment type in Transfer order .
In eWM there is a concept of warehouse process type which determines warehouse task creation with reference to reference document types
In WM printing is controlled by setting up configuration that is primarily based on movement type .
In eWM there is new concept called post processing framework.It has a condition table concept with action profiles.
From Architecture perspective:
SAP WM is primarily designed as a central warehouse which is a component of Logistics execution in the same ERP system and integrates with other logistics modules .
SAP eWM system is designed to run as a Decentralized system.Although it can be deployed in the ERP system it is more commonly considered as an application in the SCM server landscape.
From processes / functionality perspective: Given below the comparision in Yes /No format for the various functionalities offered in SAP ewM .For a similar functionality not available in SAP WM I have mentioned as No .
|Receive ASN data||Yes||No|
|ASN Validation & Correction||Yes||No|
|Transporation Unit Arrival||Yes||No|
|Manage Transportation Unit||Yes||No|
|Putaway Bin determination||Yes||Yes|
|Unload Transportation Unit||Yes||No|
|Returns / Reverse Logistics||Yes||No|
|Goods receipts optimization||Yes||No|
|Inventory Counts / Record Accuracy||Yes||Yes||eWM:inventory based on products and/or based on storage bins.New feature physical inventory during putaway|
|Freight Order Management||Yes||No|
|Kit to Stock||Yes||No|
|Picking Bin Determination||Yes||Yes|
|Warehouse Order Creation||Yes||Yes||EWM =Warehouse order / WM = Transfer order|
|Transportation Cross Docking||Yes||Yes|
|Labour Management||Yes||No||SAP WM has TRM|
|Opportunistic Cross Docking||Yes||Yes|
|RF support for processes||Yes||Yes|
|Material Flow System||Yes||No|
|Goods Receipt – Optimization||Yes||No|