Lights on Shabbos. Making sense of it.

[The One and Only Mo]

So a few weeks ago I was invited to Shabbos lunch with my mom and we got there early so we were waiting. A guy across the street was fixing a garage and he came over to chat with us. We were talking and he turned out to be Jewish. I told him I was recently ba'al teshuvah and we started talking about that. Finally, we got to Shabbos. He asked me why we can leave lights on but not T.V. I told him because T.V. represents the "every day thing" we have to avoid and the sounds and image being produced are forbidden on shabbos. He didn't like my answer. He thought they are both electricity so why is one allowed but not the other. I read an article this past shabbos about leaving t.v. on on shabbos, and the Rabbi brought down R' Moshe Feinstein who basically said you can't leave it on because it's not the spirit of Shabbos, ma'ras ayin etc. But then I started thinking about my answer to that guy about the light a few weeks ago. Maybe somebody else wants to give me some piece of mind? I told him basically having a light on doesn't take away from Shabbos in any way, but t.v. does.