How can you tell the difference between spanish and mexican people?


i honeslty can’t seem to tell the difference. They are brown and short, all seem to look the same, eat the same food and talk the same language. There’s apparently alot of both ethnicities in the town were im going to move to so would like to know the difference between the two groups because i remember a cuban guy who got really offended when i thought he was spanish.
people who keep saying they don’t look the same etc etc look at diego sanchez- he’s meaxican and he ain’t brown at all