Business Processes are basically collection of activities cutting across various departments, producing a valuable output for the customers (e.g Sales Process, Procurement Process). Workflow is used to automate these repetitive activities and hence business processes. So workflow will bring automation and efficiency to the business process.
both defines the series of task to produce some final outcome but 'workflow' is more general term than process. A process has some input and gives some ouput after performing some series of activities. in contrast, a 'workflow' may not has some input. it shows the flow of activities simply . e.g. flow of document within different departments of an organization. At each stage in the workflow, there may be a specific process. e.g. document reaching at production department, an individual or group of individuals may perform some tasks.
Agreeing with @Hans another document that corroborates his explanation, although that identifies the BPM technologies Process Aware Information Systems (PAIS) focused in two main areas workflow and case management systems.
Full story at the beginning of the thesis:
Russell, N. C. (2007). Foundations of process-aware information systems. Retrieved from http://eprints.qut.edu.au/16592/
There is another aspect related with the use of workflows isolated of BPM, that could result of doing faster the task execution, and could be criticized of "doing thinks wrong faster". In the context of the lack of processes design.
Although I understand the perspective it is also possible to make the decomposition of business processes, e.g. from high level and intrinsically related to value chain (or should be) until work level (human or machine) were we could consider the concept of Business Object as a way to clearly identify if the levels of decomposition should continue or not.
On the other hand, if a process is modeled and implemented in a BPMS there is the need of defining the data that is exchanged between activities.
Assuming this, probably could be used an abstraction of data on higher levels of processes without getting to deeply in technological aspects.
Thanks for your detailed answer Andre! I also like the different points of view of Pedro and Adrian. I think it's even more clear to me that workflow is almost like an actionable "implementation" of a business process. That is, an artefact which can enable work automation and flow monitoring by providing a more low-level model defining not only tasks and their sequence of execution, but also data abstraction, specific actors and technological details when applicable.
Everybody talks a lot on these "clear" diferences between workflow and BPMS, but nobody has presented the answer in a "clear" conceptualization, or rather, with best examples! How about to talk less in theory and more in practice?
I'd echo same, that a workflow is "an actionable "implementation" of business processes with the aim of improving productivity and assuring business outcomes".