The division of two things that are completely different refers to -

Dichotomy (noun)
English Meaning: The division of two things that are completely different.
Bangla Meaning: দ্বিবিভাগ; দ্বিবিভাজন; (সাধারণত) পরস্পরবিরোধী দুই ভাগে বা জোড়ায় বিভক্ত করা: the dichotomy of truth and falsehood.

Synonyms: Division (বিভাজন; ভাগ; বণ্টন), Separation (বিচ্ছিন্নকরণ; পৃথককরণ), Split (বিভাজন), Disunion (অনৈক্য), Differences of opinion (মতের অমিল)। 
Antonyms: Agreement (ঐক্য), Likeness (সাদৃশ্য; মিল), Similarity (আদল; অভিন্নতা), Accord (সঙ্গতি), Resemblance (সদৃশতা)। 

• Other Forms: 
-Dichotomous (Noun)
- Dichotomize (Verb)

Example Sentence: 
1. There is often a dichotomy between what politicians say and what they do.
2. The dichotomy between eastern and western culture shows it can’t be treated equally. 

অন্য অপশন গুলোর মধ্যে - 
• Reticent - Unwilling to speak about your thoughts or feelings.
• Gainsay -To refuse to accept something as the truth.

Source: Lecture.