"Å arbeide" and "Å jobbe" are synonyms, but "Å jobbe" is more considered the informal expression and "Å arbeide" is the formal expression. When you learn more about the language, you will also notice when to use then more easily. "Å leke" and "Å spille" are not synonyms. "Å leke" is mostly used for children games like tag or hide-and-seek, "De leker sisten" eller "De lekte gjemsel". "Å spille" is used for things like computer games, card games and party games, but also almost any kind of not very physically demanding activity. "Han spiller World of Warcraft" or "De spilte sjakk" Hope this makes thing a bit easier to understand, good luck with Norwegian.

"Å arbeide" is usually used to describe an odd job or manual labor, whilst "Å jobbe" commonly refers to your actual day job. "Å leke" is used to describe when you are playing as kids for example, where as "Å spille" is more used to describe sports, computer games and competitive playing generally:)

Thank you very much :D!