which is the first declination in latin? what is the difference between the two last terminations of the singular one?

rosa, rosae, rosae, rosam, rosa, rosa rosa and rosa differ for their valus: the fist one is use as a vocative, while the other one which is characterised by a long sound is used as various complements e.g the way you do, use something.

rosae, rosarum, rosis, rosas, rosae, rosis