Underage Possession of Alcohol in New York

My question involves criminal law for the state of: New York

I am wondering if there is any way to refute the charges against me or how I should approach this situation. Any help is greatly appreciated. Last night I was at a concert and a security guard was blocking an aisle way. He was off to one side so I tried to sneak by him and keep walking. I did not make it far before I was forcefully grabbed by the neck and one hand was pulled behind my back. He pulled me out of the crowded area and they called the cops over. The security guard asked if I had been drinking and I admitted I had. Then when they asked for my id I accidentally pulled out my brothers expired under 21 id and they saw it. I did not try to hide it. I admitted I had it and gave them my real id also. I had not used it that night or do they have proof of me trying to impersonate my brother. The cop told me that he could arrest me for having it but since I complied he was just going to give me a ticket for underage possession of alcohol. At the time I had no alcohol on me and I did not admit to the cop that I was drinking. He actually did not ask anything about the incident he just wrote me a ticket. On my ticket it says underage possession of alcohol in violation of sec 397.1.

You were underage, you had a false ID and you don't have to be asked for a cop to know if you had alcohol. visible signs can be evidence enough. Take your punishment and learn from your errors.

First there was no visible signs. I was barely under the influence but I thought I knew it would be better to comply then argue. Does it matter if I never actually even used the ID ever i just found it one day and kept it. I am obviously stupid enough to keep it in my wallet I admit but I am not stupid enough to actually try to use an expired under 21 id? My question was more to effect of why didn't he charge me for underage drinking compared to underage possession of alcohol. Is there an actual difference between the two? Also if I was to ask during the court date what actual alcohol I was in possession of what could he say? Do not take this as me trying to defend myself I admit I was at the wrong. I am more just curious about the situation. Thank you.

If you were barely under the influence, trust that there were visible signs and a smell. Between your interaction with security(who may or may not have been off duty police) and the on duty cop, I'm sure they had enough to warrant a citation.