Difference beween WCM and ECM

Doing some research on Content Management systems, I got a bit confused about the difference between Web content management systems and Enterprise Content Management systems.

This article is a good read to understand and appreciate the differences.
The lines between all content technology families are very blurry and hence the auhor suggests that we evaluate a product based on the scenario requirement.

For publishing company websites, intranet sites, a WCM may be a good solution. A ECM solution may be focussed towards a particular industry.