Comment and reply?

Hi guys,
I am new to wordpress and there is a question confusing me. I create some post. Also, I closed all the comment. On the bottom, there always has a text said comment are closed. Is there anyway to remove this?
In addition, I closed comment already. Some post just have a big text with text area say leave a reply. What?
Comment≠leave a reply? how to take this off? what is the different between them? Can I only have one of them? I guess that is good enough for me.