Are "welcome to ~" and "welcome aboard ~" the same?
Kind of. They both are a type of greeting, however they are used in different situations. You typically say "welcome aboard" when you get in some sort of vehicle; usually a boat or an airplane. "Welcome to" is usually used when you arrive at a particular location. Ex: Welcome aboard the Mariner of the Seas. Ex: Welcome to my home. Ex: Welcome aboard everyone. We will be taking off shortly. Ex: Welcome to Olive Garden. My name is Karen and I'll be your server this evening.