"Unusual" vs. "abnormal": the nuances of the unexpected

What is similar?
Both "unusual" and "abnormal" describe something that deviates from the norm or is not typical. Both words can often imply something unexpected or out of the ordinary.
What is different?
"Unusual" often has a neutral or positive connotation, suggesting something rare or interesting. "Abnormal" generally has a negative connotation, often used in contexts of health or scientific fields to imply something is outside the desired norm.
Which one is more common?

Examples of usage
Unusual- The sky had an unusual shade of green during the storm.
- She has an unusual talent for solving complex puzzles.
- It was unusual to see snow in April in this region.
- The doctor noted an abnormal growth on the x-ray.
- His behavior was considered abnormal for someone of his age.
- They found some abnormal results in the blood test.