Sometimes there is not a big difference. "Do you want something to drink?" is the same as "Do you want anything to drink?" But sometimes there is a big difference. Pronouns with some (someone, somebody, something, somewhere, etc.) are specific, but pronouns with any (anyone, anybody, anything, anywhere, etc.) are not specific. For example: She dates SOMEONE who drives a Mercedes. (She has one boyfriend. I don't know his name but he has a Mercedes.) She dates ANYONE who drives a Mercedes. (If you have a Mercedes, she will be your girlfriend. You can be old, short, fat, bald, mean, etc. but if you drive this car she will date you.)

"Something" es mas como decir "algo", digamos "Say something to me in Spanish" seria "Digame algo en Espanol". "Anything" es mas como decir "lo que sea", digamos "What do you want to eat? Anything" seria "Que quieres de comer? Lo que sea."

Something can be specific. Anything is intrinsically unspecific. Here is a quick example of how something is always more specific than Anything: "I want something." "What do you want?" "I want that thing, I guess." "I want anything." "What do you want?" "I just told you.... Anything."

on thing = something this thing or this thing or this thing etc = anything

Also we usually use "something" in positive sentenses and "anything" in negative sentenses. I don't have anything to read, but I have something to watch.