Many business dictionaries state that there is no difference between the terms work in process and work in progress, so it is possible to interchange the terms.
However, there is a difference based on the common usage of the terms process and progress. "Process" implies that there is a manufacturing process in place where products are created under a standardized and ongoing production system. Thus, work in process applies more readily to a manufacturing environment.
The word "progress" implies a longer-term period during which a product is completed, possibly covering a number of accounting periods. Given the implied duration, this means that work in progress more readily applies to longer-term consulting projects and customized product work. In both cases, there is no highly engineered process in place for arriving at a final product, as would be the case in a manufacturing environment.
These concepts do not apply to construction projects, for which there is a separate construction-in-progress account that accumulates costs. Once a construction project has been completed, the balance in this account is shifted into a fixed assets building account and then depreciated.
In short, there are differences in how you can use the terms work in process and work in progress - however, these are fine distinctions, so you should be able to use either term in most cases.