Employees that I work with are down talking me because I want to stay late.?

This guy who is down talking to me keeps telling me oh you can't stay late, you shouldn't stay late and why are you staying late. This guy isn't even my supervisor. Basically I stay late 30 mins after my shift ends to catch up and finish for the day and this guy down talks me about it. It's unpaid and I don't mind because I'm catching up. What I don't understand is he comes in 30 mins before his shift to start working which is unpaid as well for him. What is difference between his coming in early for 30 mins of unpaid work and me staying late? He doesn't seem to mind what he does and he constantly reminds me I can't get overtime. Which I don't care because I genuinely enjoy what I do. How can I approach this and what should I do? I don't want to start drama but it's annoying. Every time he tells me something it doesn't pop in my mind that he is basically doing the same thing but coming in super early.