Well, the second syntax is the one you would normally use if the method is intended to return a new, freshly constructed, independent instance of the class. If that's not the case, then future developers of your code might look at it and mistakenly assume that this,
meshInstance2 = meshInstance1.initializeMesh(tempVertices,tempFaces)
will result in separate instances of the class meshInstance1 and meshInstance2.That can be a dangerous mistake to make. In later lines of code, you think that manipulations of meshInstance2 are not affecting meshInstance1, when in fact they are.
