Are "check it out" and just "check it" different?
Yes, depending on context these carry different meanings. "Check it" is often used in a slang and informal way to get someone's attention. Formally it's an imperative command asking someone to examine something. Ex: The tire seems to be low on air can you please check it. "Check it out" however could be used instead of "Look at this/that!", which is how it is being used here, or calling for someone to look into something in more detail. Ex: Check it out. I got new shoes. Ex: It's a great movie you have to check it out.