Some of the features that differentiate the Ukrainian language from other Slavic languages as well as make it unique are:
1) the vowel sound [e] doesn't soften the consonant that comes before it, for example: теплий, село, небо;
2) hissing, lip and [r] sounds at the end of a word are always hard, for example: плащ, голуб, повiр;
3) in the Ukrainian language, there is a complex future tense of verbs, for example: писатиму, читатиму, працюватиму;
4) alternation of consonants [g], [k], [h] and [s], [ts], [s] in case nouns, for example: нога‒нозі, рука‒руці, вухо‒вусі.
5) In the Ukrainian language, unlike in other eastern Slavic languages, the noun has 7 cases, one of which is vocative.
6) In the Ukrainian language, there are many synonyms. For example, the word "horizon" has 12 synonyms: обрій, небозвід, небосхил, крайнебо, круговид, кругозір, кругогляд, виднокруг, видноколо, виднокрай, небокрай, овид.
7) One of the special features of the Ukrainian language is that it is rich of diminutives: водичка, легенький, гарнесененький, миленький and more.
8) Ukrainian is a very harmonious language. It avoids the confluence of hard to pronounce consonant and vowel groups.
‒What you have mentioned are the special features of the Ukrainian language? That's how it is different from other Slavic languages?
Yes. These are the spacial features of the Ukrainian language. It belongs to the Indo-European language family and East Slavic group of languages. The features that I have listed are the ones that differentiate it from other Slavic languages.