Bu elma daha tatlı.
English: This apple is sweeter.
In Turkish, 'üstünlük ekleri' are suffixes used to form the comparative and superlative degrees of adjectives and adverbs. They help you compare things or show the highest degree.
Use 'daha' to compare two things, showing that one has more of a quality than the other. Use 'en' when you want to express that something has the most of a quality among a group.
Bu elma daha tatlı.
English: This apple is sweeter.
Ali daha hızlı koşuyor.
English: Ali runs faster.
En güzel şehir İstanbul.
English: The most beautiful city is Istanbul.
En yüksek dağ Ağrı Dağı.
English: The highest mountain is Mount Ararat.