Can you help me understand the difference between gender identity and gender expression

I have googled it a few times but I'm still a little confused. I understand that gender identity is how you feel and how you identify. Is that right? And that expression is how you present yourself? Like clothing choices and stuff? But I guess what I'm not understanding is how you identify as a gender. I'm just confused a bit so if anyone could try to clear this up, I'd appreciate that. I did try to figure it out myself, but I am having trouble.