2. Jeans are more comfortable than a suit. They may be more comfortable but they are less official.
3. Life in the country is less noisy than life in the city. It may be less noisy, but it is not as comfortable.
4. Department stores have a wider selection of clothes than other shops. They may have a wider selection but they are not as cosy as small shops.
5. The supermarket outside town offers cheaper goods. The goods may be cheaper but the selection is not as good as it is in the city centre. (пятое предложение не до конца видно, поэтому сравнение-из головы)