Both疼 and 痛 can be used to express that someone feels discomfort on the body.
疼 is usually used to express that someone cares for sb./sth.
痛 is usually used to describe that someone feels sad came from a （psychological or emotional） impact, and the pain is felt more strongly.
疼 can be used as a verb with objects following it (疼+Objects). It means love dearly/ be fond of.