To start and to begin. I cant start the day without coffee. I begin every day with a cup of coffee. Begin, when used as transitive verb, means "start, perform, or undergo the first part of an action or activity." Start, when used as transitive verb, means "cause (an event or process) to happen", or "cause or enable someone or something to begin doing or pursuing something." this is the same in both Norwegian and English :)

They're the exact same. You can use them interchangeably.