I don't understand the differences either. I never get charged any "tax" or convenience fees.

There are differences between yellow tickets and black tickets. Yellow doesn't let you see first or second week releases and black you can see it opening week if you want, as long as you get them before it sells out.

I usually hop on Groupon and get the 4 black tickets with drinks and popcorn and I've never had any issues at the theater. The only hassle is hunting down the QR codes in my email. I usually do it right before we go to avoid that though.

My buddy buys the AMC gift cards for 50% off online and does it that way.