What is the difference between a research center and a research institute?

Specifically dealing with social and policy research, if that makes a difference.What is the difference between a research center and a research institute?
I'm not sure there is a specific distinction between the activity that those two bodies carry out. However, in my experience the term "center" is more often used when referring to an academic research body (e.g. a policy school at a university whose professors or even students produce research), and "institute" is more widely used for nonprofits that are mostly nonpartisan and whose staff carries out research on a regular basis. I'd say that the actual research produced by an academic center is obviously more in the form of white papers and journal submissions, and independent nonprofits often prepare research reports that are more appealing to a broader audience. Either way, both academic centers and freestanding organizations are usually nonprofits, meaning that they are tax-exempt.