Contrast, the root word of these words, means to differ in an immediately noticeable way. You could say: "The blue sky exquisitely contrasts the golden fields stretching beyond the horizon." Given the meaning of contrast we can now infer what contrasting and contrastive mean by looking the suffixes. -ing, I'm sure you've learned that one by now. So contrasting, the gerund of contrast, must be the act of being in contrast. "Quality journalism should always offer contrasting perspectives." Now you may not have learned what this is yet. -ive is a suffix used on verbs to create adjectives which describe the ability to perform the verb. "Every language is contrastive outside it's native region."