I would say so.
"Thinking about you" means that you're actually thinking thoughts about a person.
"Thinking of you" to me has a couple of meanings. One is more like "Something reminded me of you." For example, let's say your favorite ice cream is strawberry banana swirl. Then I could say, "I went to the supermarket and thought of you when I saw they had strawberry banana swirl ice cream."
Another meaning for "Thinking of you" is related to the word "thoughtful." For example, let's say I bought you some strawberry banana swirl ice cream. You could then say, "Thanks for thinking of me."
Hope this helps!