" Worry" is a verb. "I worry about my brother". This suggests that you worry about him constantly. "Worried" is the past/past participle of the verb. It can be used as an adjective in the same way as past participles such as bored, excited, embarrassed, interested and frightened can be used. You can say "I'm worried about my brother". This is using "worried" as an adjective, describing how you feel at the moment.

I believe they are just different usages to mean the same thing. To worry Rock climbing is a dangerous sport! I worry about you when you go. To be worried My friend had a rock climbing accident, and he's now in hospital. I'm very worried about him. Laurence

Thank you very much.