Here are some example sentences using contrast transition words:

• The first pen is cheap, but the second pen is expensive.
• The movie was entertaining. However, the ending was disappointing.
• The restaurant has great food. On the other hand, the service is slow.
• The company lost money last year. Nevertheless, they are still expanding.
• The house is small. In contrast, the yard is huge.
• I love coffee. Whereas, my sister prefers tea.