I agree with ಠ-ಠ.
"Distinctly different" is a common redundant phrase. If two things are distinct, they should be different enough that it is obvious. "Distinctly different" implies that it does not take much "discernment" to "distinguish" between the two things.
There is also the phrase "a distinction without a difference". This means that that it is possible to distinguish two things, but that the difference between them does not matter in any way that is important (to the author).
In addition to the relevant definition ಠ-ಠ provides, "differentiate" has a mathematical meaning. In mathematics, "differentiate" means "calculate the derivative". This term is derived from the use of "differences" in calculating the slope of an infinitesimally short portion of a curve.