The difference between these terms refers to their general appearance. Crystallized mineral means the one assuming a crystal form - normally consisting of macro size crystals visible by bare eye see, for example:
Crystalline is the mineral that exhibits a crystal structure (in contrast to an amorphous one, glassy etc.) Crystalline mineral does not necessarily shows up as beautiful crystals. Clays, for example, are most often crystalline, but have a "dirty soil" appearance.
Well, I wouldn't make a big deal and guess it is more a language problem than describing different things. If a mineral has been crystallized it describes the process of crystallization. The term crystalline describes the property of a solid material, i.e. it is simply an adjective.